The placenta is grown by the baby, not the mother, and it strips the muscle out of her arteries so they cannot squeeze shut

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48 more stories on this beat.

Each with its own sources. None of these is a link to the story above.

1. 02

   Accreta traced to the scar, not the placenta

   Placenta accreta is when the placenta grows so far into the womb wall that it will not come away after birth, and the mother can bleed to death. It now affects roughly 14,000 pregnancies a year. A UCLA Health team led by Yalda Afshar took tissue from 13 women who had it and 10 who had the risk factors but not the condition. Where an old cesarean scar had healed with tangled rather than neatly aligned collagen, the normal boundary between womb and placenta broke down. [14]

   Why it matters — It moves the fault from the placenta to the mother's scar. That would mean the danger could be read before a pregnancy starts, rather than found on the operating table. [14]

2. 03

   The condition rose with the cesarean rate

   Accreta used to be a curiosity. One review traces it from about 1 in 2,562 to 4,027 births in the late 1970s to 1 in 731 by the late 2000s. A separate study of US delivery records moves it from about 3 per 10,000 deliveries in the 1930s to 1950s to about 17 per 10,000 in 2012 to 2021. A review of 1.7 million cesarean deliveries found it in about 1 in 313 of them. Every account names the same driver: more cesareans, more scars. [15][12]

   Why it matters — Nothing about the placenta changed. A surgical decision taken in one pregnancy sets the ground the next placenta will be built on. [15]

3. 04

   Two cases with no scar at all

   Accreta is supposed to need a scar, and two case reports show it does not always. A 42-year-old woman with a severe inherited blood disorder, pregnant after IVF, arrived at 30 weeks in shock; surgeons found her womb ruptured from behind and the placenta grown through the wall. She died of bleeding they could not stop. A second woman, with no previous surgery of any kind, had a placenta grown through the outer wall of the womb at 32 weeks and survived a hysterectomy. [20]

   Why it matters — It is the exception that keeps the scar theory honest. Something else can produce the same result, and nobody has named what. [20]

4. 05

   The scar pregnancy that comes first

   A cesarean scar pregnancy is an embryo that implants directly in an old surgical scar instead of healthy womb lining. Reviews now treat it as the earliest form of accreta rather than a separate accident, and its numbers are climbing with the cesarean rate. Grading systems have multiplied, mostly disagreeing over how much muscle is left between the pregnancy sac and the bladder. An NHS hospital guideline in England sets out how to spot it and says several specialties must manage it together. [21][22]

   Why it matters — The same scar produces the emergency at six weeks and the bleeding hysterectomy at 36 weeks. Naming them one condition changes who gets watched from the start. [21]

5. 06

   One scar pregnancy, caught early

   A 32-year-old woman came in at six and a half weeks pregnant with cramping and bleeding. An ultrasound probe showed the pregnancy sac sitting inside her old cesarean scar. Pregnancy doctors and interventional radiologists injected methotrexate, a drug that stops fast-dividing cells, straight into the sac under ultrasound guidance, then pressed on the site with a balloon catheter. Her pregnancy hormone level fell quickly and the ectopic pregnancy resolved. The authors note there is still no standard protocol for this. [23]

   Why it matters — This is one case and the authors say so; it is not evidence of a best method. What it shows is the condition being found early enough for there to be options at all. [23]

6. 07

   Grading accreta by place, not depth

   For decades accreta has been graded by how deep the placenta went, in three steps from accreta to increta to percreta. A 2026 paper argues that depth does not reliably predict how hard the surgery turns out to be, or who could keep their womb. It proposes grading by location instead: where the lesion sits, the shape of the lower womb, whether the cervix is involved, and how the pelvic blood vessels have rearranged themselves. [24]

   Why it matters — A grading system decides who is sent to a specialist centre and who is not. Changing what it measures changes who is treated as high risk. [24]

7. 08

   The blood test that reads the placenta

   Preeclampsia is diagnosed by blood pressure and protein in the urine, which show up late. A blood test reads two placental signals instead: sFlt-1, which a struggling placenta pours out, against PlGF, a growth factor a healthy one makes. A study of 1,329 pregnant women with high blood pressure in southern China derived and then checked its own cut-offs, landing on a ratio of 74 before 34 weeks and 95 after it for predicting preeclampsia within a week. [19]

   Why it matters — It shifts the question from what the mother's body is showing to what her placenta is doing, days before she feels anything. [19]

8. 09

   Every study gets a different threshold

   That ratio has no agreed number behind it. One widely used pair of cut-offs is 85 for early preeclampsia and 110 for late. The stillbirth study above used a standard clinical cut-off of 38. A US cohort of 465 pregnancies found the best cut-off was 33 overall, and 50 among women who already had high blood pressure. In that cohort preeclampsia followed within two weeks in 9.7% of everyone tested and 37% of the hypertensive group. The Chinese cohort derived 74 and 95. [19][25][16]

   Why it matters — A test with seven thresholds is not one test. Which number a hospital uses decides who gets admitted and who is sent home. [25]

9. 10

   A high ratio and stillbirth

   Researchers at the Harvard T.H. Chan School of Public Health compared 39 stillbirths with 86 live births in Bangladesh, measuring the mother's sFlt-1 to PlGF ratio. A high ratio at the standard clinical cut-offs came with roughly 13 times the odds of stillbirth. The paper was published in JAMA Network Open in 2026 and its authors argue that the same placental signal imbalance behind preeclampsia may be driving stillbirths in places with few obstetric services. [16]

   Why it matters — Most work on this test has been done in well-resourced hospitals. This is a measurement of what the placenta is doing where almost nobody is measuring it. [16]

10. 11

    The same signal in growth-restricted pregnancies

    A hospital in Antwerp reviewed 85 pregnancies where the fetus was growing too slowly and the mother's sFlt-1 to PlGF ratio had been measured, between January 2022 and October 2024. Seventy-five had a raised ratio and ten did not. In the raised group, abnormal blood-flow scans, fetal death and preeclampsia were all more common, and the babies had more breathing problems, more bleeding into the brain and more infection. A separate 2025 study tested the same ratio in twin pregnancies. [26][27]

    Why it matters — Slow growth has many causes. The ratio is being used to sort the ones that come from a failing placenta from the ones that do not. [26]

11. 12

    Fat particles that reached the placenta in mice

    There is no proven drug that slows preeclampsia; the standard route is to deliver the baby. A team led by Michael Mitchell at the University of Pennsylvania screened 98 formulations of lipid nanoparticles, tiny fat bubbles used to carry genetic medicines, looking for one that lands in the placenta. LNP-55 delivered almost 200 times more of the test compound there than the industry standard. A single injection carrying VEGF mRNA held a pre-eclamptic mouse's blood pressure down for the rest of the pregnancy. [11]

    Why it matters — It is a mouse result and the researchers say more work is needed before humans. It is also the first thing in this field aimed at treating the placenta rather than removing it. [11]

12. 13

    The immune cells that help the invaders

    The fetus's invading cells are half foreign to the mother, and the most common immune cell in the pregnant womb lining is a natural killer cell, whose usual job is destroying foreign cells. In pregnancy they do the opposite. Decidual natural killer cells shape how far the fetal cells migrate and help them convert the mother's spiral arteries into wide, open vessels. The fetal cells in turn change how those immune cells behave. [3]

    Why it matters — The interface is not the mother tolerating an intrusion. Her own immune cells are part of the building crew. [3]

13. 14

    When the womb does reject the placenta

    Chronic histiocytic intervillositis is a rare condition in which the mother's immune cells flood the spaces where her blood washes around the fetal tufts. It causes miscarriage and severe growth restriction, and it comes back in later pregnancies at a high rate. A 2026 review reports that nobody knows what sets it off: autoimmune disease, viral infection and the genetic match between mother and fetus have all been proposed. Treatments tried include immune suppressants, blood thinners and antibody drugs. [28]

    Why it matters — It is the counter-example to everything above. The tolerance the placenta depends on is not guaranteed, and when it fails the pregnancy usually ends. [28]

14. 15

    Inflammation stops the burrowing

    Dutch researchers grew trophoblast organoids, small lumps of placental tissue in a dish, and exposed them to two inflammatory signalling molecules, interferon-alpha and tumour necrosis factor alpha, which run high in autoimmune disease. The cells still matured normally into the invading type, but they invaded much less, in the organoids and in co-cultures with womb lining tissue. Genes driving invasion were turned down. The authors link this to why lupus pregnancies so often go wrong. [29]

    Why it matters — It supplies a mechanism for something obstetricians already see: mothers with inflammatory illnesses get more preeclampsia and more growth restriction. [29]

15. 16

    Antibodies are pumped, not handed over

    A newborn is born with almost no immune memory of its own, and arrives carrying its mother's. A pump in the placenta called FcRn moves immunoglobulin G, the main long-lasting antibody, from her blood to the fetus, starting around week eight and running hardest between weeks 28 and 40. By full term the baby's antibody set matches its mother's. A 2026 review sets out how preterm birth, high blood sugar and maternal infection all disrupt the transfer. [9]

    Why it matters — It is why a vaccine given to a pregnant woman can protect a baby who cannot be vaccinated yet, and why a baby born early gets less of that protection. [9]

16. 17

    Borrowed antibodies can block the baby's own

    That handover then gets in the way. Maternal antibodies that crossed the placenta can bind to a vaccine given to the infant later, clearing the vaccine before the baby's own immune system responds to it. This is documented for measles, tetanus and polio. Vaccination during pregnancy or breastfeeding produces protective antibodies in milk too, and a 2026 review reports that milk antibodies from vaccinated mothers also sped up clearance of vaccine and cut the infants' own responses. [30]

    Why it matters — Protection handed down and protection built from scratch are in direct competition, and the schedule for infant vaccines has to be set around that. [30]

17. 18

    When the mother's antibodies attack the baby's liver

    Gestational alloimmune liver disease is a rare condition in which antibodies from the mother cross the placenta and destroy the fetal liver, causing liver failure at or before birth. A single-centre study followed seven women whose first affected pregnancies produced five newborn deaths. In ten later pregnancies, all seven received high-dose immunoglobulin by drip, one gram per kilogram of body weight each week from a median of 14 weeks, a median of 23 doses. None of those babies developed severe disease. [31]

    Why it matters — The same pump that carries protection carries harm, and the treatment works by flooding the pump with harmless antibody. [31]

18. 19

    A muscle disease that crosses for a few weeks

    Myasthenia gravis is an autoimmune disease in which antibodies block the signal from nerve to muscle, causing weakness. It most often starts in women of childbearing age. A 2026 review reports that flare-ups cluster in the first trimester and after birth, and that some babies are born with transient neonatal myasthenia, temporary weakness caused by the mother's antibodies crossing the placenta, which fades as those antibodies clear. Some immune-suppressing drugs used for the disease cannot be used in pregnancy. [32]

    Why it matters — The newborn weakness is the clearest proof that the transfer is real: the baby has the illness for as long as the borrowed antibodies last, and then does not. [32]

19. 20

    Fetal cells stay in the mother for decades

    Cells cross the placenta in both directions. Fetal Y-chromosome DNA has been detected in a mother's blood as early as seven weeks of pregnancy, before her circulation to the placenta is fully open. Those cells are not cleared at birth. A 2026 review of the field reports that both fetal cells in mothers and maternal cells in children have been found decades after the birth, and that how they survive that long is still an open question. [33][34]

    Why it matters — Pregnancy is usually described as ending. On the evidence of the cells, part of it does not. [33]

20. 21

    Carrying male cells, and cancer

    Because male fetal cells can be identified by their Y chromosome, they are the easiest to count. A meta-analysis pooled twelve studies covering 3,078 women and found that those carrying male cells had roughly half the cancer rate of those who did not, a pooled relative risk of 0.51. Ovarian cancer risk was 56% lower in one study. Colon cancer went the other way, running higher in women who carried the cells. [35]

    Why it matters — The direction of the effect flips by organ, which means whatever is happening is not one simple thing, and the authors do not claim it is. [35]

21. 22

    A proposal about breast cancer, not a finding

    An opinion article in a Frontiers immunology journal proposes that carrying a pregnancy exposes a woman's immune system to the father's tissue markers, and that the tolerance this builds could in principle also shelter an early breast cancer. The authors note that in a natural pregnancy the fetus differs from the mother at half of those markers, and in a surrogate pregnancy at all of them. They present it as a hypothesis worth testing. [36]

    Why it matters — It is included here as an argument, not as evidence. The same tolerance that lets a pregnancy work is being asked to explain something much larger, and nobody has tested it. [36]

22. 23

    Kidneys from husband to wife

    When a woman receives a kidney from her husband, her immune system may already have met some of his tissue markers, because she carried his children. A 2026 review found that overall survival of patient and graft is acceptable with modern screening. But it also found early rises in antibodies aimed at the donor, inflammation in the small vessels, and antibody-driven rejection more often than in other living-donor pairs. [37]

    Why it matters — Transplant surgery is here reading a record written by pregnancy years earlier, in a woman who never knew it was being written. [37]

23. 24

    The hormone that raises the mother's blood sugar

    The placenta is also a hormone factory, and by the end of the first trimester it has taken over most hormone production from the ovary. One of its hormones is human placental lactogen. It makes the mother's own cells respond less to insulin, so sugar and fat stay in her blood instead of being stored, and more of both reaches the fetus. Insulin resistance rises steadily through the second and third trimesters as a normal part of pregnancy. [7][8]

    Why it matters — It is the plainest example of the placenta acting on the mother rather than on the fetus, and the same mechanism pushed too far becomes gestational diabetes. [8]

24. 25

    When that mechanism goes too far

    Gestational diabetes is high blood sugar that first appears in pregnancy, and the placenta sits in the middle of it. Placental hormones drive the insulin resistance that is normal in pregnancy; in gestational diabetes that resistance is excessive and the mother's insulin-making cells cannot keep up. A 2025 review argues the placenta is also a victim, being packed with mitochondria and therefore easily damaged by the high-sugar environment, with damaged fats triggering a form of cell death. [38]

    Why it matters — The condition is usually described as the mother's. The organ that helped create it is the fetus's. [38]

25. 26

    Turning down one brake made mouse fetuses bigger

    DEPTOR is a protein that puts a brake on mTOR, a switch inside cells that senses nutrients. Researchers bred mice in which DEPTOR was knocked down only in the placenta. Those placentas showed more mTOR activity, more amino acid transport across the membrane, and bigger fetuses. In human placentas collected at birth, DEPTOR levels were lower in the ones from unusually large babies, and fell as birthweight rose. [39]

    Why it matters — It shows the supply rate has a dial, and that the dial is inside placental tissue rather than in the mother. [39]

26. 27

    A missing enzyme starved the embryo

    An enzyme called p110-beta had no clearly known job, and mice bred without a working version of it mostly die before birth for reasons nobody could explain. Researchers examined those embryos in detail. The embryos themselves looked normal but were small, and the placentas were small, with a shrunken nutrient-storing zone and much less of the transporter system that moves amino acids from mother to embryo. [40]

    Why it matters — The lethal defect was not in the embryo. It was in the organ the embryo builds, which is where fetal growth restriction usually starts. [40]

27. 28

    A weak placenta reaches into adulthood

    Researchers deleted mTOR, the nutrient-sensing switch, from the placenta alone in mice. Placentas came out smaller and damaged inside, with malformed mitochondria, and both male and female fetuses grew poorly. The female offspring had less insulin in their blood before birth and immature insulin-making cells. As adults those same females put on more weight on a rich diet, became insulin resistant, and could not build the extra insulin-making capacity to cope. [41]

    Why it matters — The organ is gone within an hour of birth, and what it did was still measurable in a middle-aged animal. [41]

28. 29

    Placental weight predicts birth weight

    A Greek team collected placentas from 60 women between 2022 and 2024, half from pregnancies where the fetus had grown too slowly and half from normal ones, and weighed and measured each one. Placental weight, surface, volume and widest diameter were all significantly lower in the growth-restricted group. Placental weight tracked birth weight closely, and in the statistical model it was the only measurement that independently predicted it. Cords attached at the edge rather than the centre were also more common in the restricted group. [42]

    Why it matters — The oldest and cheapest measurement in the room, a set of scales, carried more information about the baby than anything else they measured. [42]

29. 30

    The cord is coiled for a reason

    The umbilical cord carries one vein bringing oxygen and food in and two arteries taking waste back out, wound around each other in a helix. Researchers modelled how much oxygen and heat leak between vessels running that close together. The coiling does increase the leak, and their model predicts that the actual arrangement of vessels in a human cord tends to keep that leak small, which matters because a large one would upset the fetus's temperature. The same leak feeds the cord's own tissue. [43]

    Why it matters — A shape everyone has seen in a delivery-room photograph turns out to be doing arithmetic about heat. [43]

30. 31

    Most birth defects happen before the barrier exists

    The placenta is routinely described as a barrier that shields the embryo from harmful substances. A review published in September 2025 lined up the timing. The critical window for most structural birth defects, including neural tube defects, cleft lip and palate, limb malformations and the defects of fetal alcohol syndrome, falls in the third to sixth week of human development. The mature human placenta is not finished until somewhere between eight and twelve weeks. Birth defects occur in about 1 in 33 births. [17]

    Why it matters — The organ credited with protection is not built yet during the weeks that matter most, so whatever protection exists in that window comes from something else. [17]

31. 32

    Nobody knows what crosses

    Pregnant women are almost always excluded from drug trials, so the evidence on what reaches a fetus comes from laboratories rather than from patients. A 2025 review counted the whole field: seven studies using cell layers covering eight drugs, 28 using whole placentas perfused with fluid after birth covering 34 drugs, six using placenta-on-a-chip devices covering five, and 39 computer simulations covering 42. Antivirals, antibiotics and opioids were the most studied. [44]

    Why it matters — Doctors prescribe in pregnancy every day. For most drugs the crossing rate is an estimate from a machine, not a measurement from a person. [44]

32. 33

    Forty years of antidepressant results that disagree

    Antidepressants of the SSRI family are among the drugs most often taken through a pregnancy. A 2026 review went through the studies published from 1983 to 2025 and found the conclusions still conflict, with some reporting benefit for mother and baby and others reporting risk. The authors single out a specific hole: almost nothing is known about SSRI use in older mothers, at a time when the average age of a first pregnancy has moved past 30. [45]

    Why it matters — This is what the evidence looks like for a common drug that has been studied for four decades. Deciding anything about a particular pregnancy is a question for a doctor who knows the case. [45]

33. 34

    Zika damaged the placenta itself

    A study published in the New England Journal of Medicine in 2016 tested blood and urine from 88 pregnant women in Rio de Janeiro. They had all come to a clinic with a rash between September 2015 and February 2016, and the researchers were from UCLA and the Fiocruz Institute in Brazil. Among those who tested positive for Zika virus, 29% had serious problems: fetal death, a placenta failing with little or no amniotic fluid, restricted growth, and damage to the fetal nervous system including possible blindness. Problems appeared at 8, 22, 25 and 35 weeks. [46]

    Why it matters — The virus was thought to act on the fetal brain. This showed it also wrecks the organ feeding the brain, which can kill a fetus that the virus never reached. [46]

34. 35

    The placenta makes its own antiviral

    The placenta is fetal tissue defending itself. Researchers grew trophoblast organoids from human placentas and found they constantly make interleukin-27, a signalling molecule, along with its receptor. Blocking that signal let Zika virus in; the signal switched on antiviral genes and held the virus back. In mice with congenital Zika infection, the same signalling kept the amount of virus in the placenta down and reduced harm to the fetus. [47]

    Why it matters — The barrier is not passive tissue. It runs its own immune response, made by the fetal side, against infections coming from the maternal side. [47]

35. 36

    The virus that got past it

    A team performed full autopsies on 18 fetuses after their mothers were infected with SARS-CoV-2, analysing 538 samples across 32 tissue types. The virus was found widely distributed in fetal organs, showing it can cross. The longer the gap between the mother's infection and the end of the pregnancy, the less often infection was found in fetal organs. Protein analysis of infected organs showed DNA damage and a disturbed immune balance. [48]

    Why it matters — It is the most complete map of where a virus goes once the placenta fails to stop it, and it was only possible after a pandemic that infected millions of pregnant women. [48]

36. 37

    Signals from the placenta may reach the fetal brain

    Placental cells release extracellular vesicles, tiny membrane bubbles carrying RNA, proteins, fats and neurotransmitters. A 2025 review argues that these may cross both the placenta and the developing blood-brain barrier, and so take part in how the fetal brain is built and patterned. Their contents change with the stage of pregnancy and with what the mother is exposed to, including air pollution, viral infection and chemicals. [49]

    Why it matters — If it holds up, the route from the mother's environment to the child's brain runs through packets the placenta posts, not just through what crosses passively. [49]

37. 38

    Womb infection and newborn brain injury

    Chorioamnionitis is infection and inflammation of the membranes around the fetus, and it is a common trigger of preterm birth. A review traces the path from that infection through the placenta's immune signalling to injury in the developing fetal brain, including changes to the networks of connections that are being laid down. The authors argue the placenta can be read after birth as a record of what the fetal brain went through. [50]

    Why it matters — An organ normally thrown away within the hour holds the evidence of an injury that will not show up in the child for years. [50]

38. 39

    Reading the placenta before birth

    Ultrasound is still the main way to look at a placenta, using structure and blood flow. Two other approaches are advancing. Photoacoustic imaging, which measures the light absorbed by haemoglobin to read blood oxygen directly, is being tested for placental use. And a team ran 56 placental MRI scans on a 0.55 tesla scanner, far weaker and cheaper than the 3 tesla machines all previous work used, and got the same spatial patterns of oxygenation and diffusion across pregnancy. [51][52]

    Why it matters — A weak scanner is a cheap scanner and one that fits in more hospitals, which decides whether placental imaging stays a research tool. [52]

39. 40

    Growing the placenta in a dish

    The human placenta is hard to study because you cannot experiment on a pregnancy, and animal placentas are built differently. Researchers are building substitutes: microfluidic organ-on-a-chip devices that mimic the maternal-fetal barrier, spheroids and organoids grown from real trophoblast, engineered scaffolds and computer models. A 2026 review sets out how far each has got and what each still cannot do. [53]

    Why it matters — Every drug question, every infection question and every invasion question above is now being asked in these models, because there is nowhere else to ask them. [53]

40. 41

    A placenta at the front is usually nothing

    An anterior placenta is one that has implanted on the front wall of the womb, between the belly and the fetus. Cleveland Clinic, a US hospital group, describes it as occurring in up to half of all pregnancies and as causing no health problems for mother or baby. It can make fetal kicks harder to feel, especially early on, and can make the heartbeat harder for a clinician to find. [54]

    Why it matters — It is included because it is the commonest thing a scan report will say about a placenta, and the honest answer is that it does not mean anything. [54]

41. 42

    When the placenta comes away too early

    Placental abruption is the placenta separating from the womb wall before the birth is finished. It happens in roughly 0.4% to 1.0% of pregnancies and is a leading cause of bleeding in the second half of pregnancy, risking haemorrhage and death for the mother and the fetus alike. The NIH reference text says it starts suddenly and with no warning, so the whole clinical response is built around spotting it fast. [55]

    Why it matters — Everything else here is about the connection being made wrong. This is the connection being broken while it is still needed. [55]

42. 43

    When the supply is simply not enough

    Placental insufficiency is the term for a placenta that does not deliver enough blood. The NIH reference text traces it to the same origin as preeclampsia: fetal cells that did not invade far enough, and spiral arteries left half-rebuilt. It underlies growth restriction, low amniotic fluid and stillbirth. Diagnosis rests on growth measurements and Doppler blood-flow scans. The listed responses include low-dose aspirin and closer surveillance; whether any of it fits a particular pregnancy is a question for a doctor. [56]

    Why it matters — It is the same defect as the lead story, named from the fetus's side rather than the mother's. [56]

43. 44

    Capsules sold as regenerative, found to hold blood

    Police in a criminal case seized unlabelled soft capsules being sold as therapeutic and regenerative food supplements. Forensic scientists ran them through mass spectrometry, infrared spectroscopy, chemiluminescence and microscopy. The capsules held biological material of unknown origin, including blood-derived compounds, fats and cell structures. The authors could not say whether this was deliberate faking or severe contamination, and did not run DNA typing on the small amount of material seized. [57]

    Why it matters — Placental and other tissue-derived capsules are sold in an unregulated market with no requirement to say what is in them, and this is what happens when someone finally checks. [57]

44. 45

    Gut bacteria proposed as a preeclampsia trigger

    Nobody knows what starts preeclampsia. A 2026 review sets out one candidate chain: the mother's gut bacteria shift during pregnancy, and packets released by placental cells carry microRNAs, proteins and fats into her circulation where they act on the whole body. The authors propose a gut-to-placenta axis running in both directions and driving the disease forward. They present it as an emerging concept rather than a settled mechanism. [58]

    Why it matters — Preeclampsia has had a proposed first cause every few years, and each one has to explain why the disease only ends when the placenta leaves. [58]

45. 46

    Hunger reaches the fetus through one gene

    Researchers combined single-cell sequencing of human and mouse placentas with data from growth-restricted human placentas, and picked out a gene called GAB1 as a link between a mother going short of food and a fetus growing badly. In mice, restricting food stunted fetal growth and disrupted the exchange layer of the placenta. In lab-grown trophoblast, nutrient restriction made the GAB1 protein unstable and it was broken down by the cell's own recycling machinery. [59]

    Why it matters — It puts a specific molecule between a mother's diet and her fetus's size, in an organ that is supposed to buffer exactly that. [59]

46. 47

    Lactate is a signal, not just waste

    The early placenta runs in low oxygen and burns sugar the fast way even when oxygen is available, the same trick tumours use, so lactate builds up and the area turns acidic. A 2026 review argues that this lactate is not waste but a signal steering the rebuilding of the mother's spiral arteries, acting on the fetal cells, the artery muscle, the immune cells and the vessel lining. Disturbed lactate handling has been linked to recurrent miscarriage, preeclampsia and growth restriction. [60]

    Why it matters — The chemical everyone learned about as a by-product of hard exercise turns out to be carrying instructions in the one place a wrong instruction is most costly. [60]

47. 48

    Micronutrients and depression after birth

    Depression around the time of birth is common, and the demands of pregnancy make shortages of vitamins and minerals more likely. A systematic review published in November 2025 gathered 58 studies that measured micronutrient levels in blood and assessed depression using validated rating scales. Of those, 31 reported a significant inverse association, meaning lower levels of a nutrient went with more depression. The other 27 did not. The authors treat the finding as an association and not a cause. [61]

    Why it matters — Thirty-one studies point one way and 27 do not. That is what an unsettled question looks like before anyone is told to act on it. [61]

48. 49

    Medicines for pregnancy are last in the queue

    Long-acting medicines, given as an injection every few months rather than as daily pills, are moving into mainstream treatment. A 2026 review from a workshop convened by the University of Liverpool and funded by Unitaid warns that pregnant and breastfeeding women, routinely excluded from trials, are on course to be left behind again. Most women take medicines during pregnancy, and the data gaps make dosing decisions guesswork. [62]

    Why it matters — It is the same exclusion that produced the drug-crossing gap above, arriving in a new class of medicine before anyone has fixed it. [62]