Children conceived through IVF carry slightly elevated risks for a handful of health outcomes, including preterm birth, low birth weight, and certain birth defects, compared to children conceived without assistance. But “slightly elevated” is the operative phrase. The absolute differences are small, and the vast majority of IVF-conceived children are born healthy and develop normally. Untangling what drives the extra risk has turned out to be surprisingly complicated, because the procedure, the embryo’s lab environment, and the underlying infertility of the parents all seem to play a role.
Preterm Birth and Low Birth Weight
The most consistent finding across decades of research is that IVF singletons are more likely to arrive early and weigh less at birth than naturally conceived singletons. A systematic review and meta-analysis of studies that controlled for at least maternal age found that IVF singletons had roughly 1.8 times the risk of preterm birth and about 1.6 times the risk of low birth weight compared to spontaneously conceived singletons. On average, IVF singletons weighed about 97 grams less and arrived about half a week earlier.1PubMed. Preterm birth and low birth weight among in vitro fertilization singletons: a systematic review and meta-analyses An earlier meta-analysis reported similar patterns and also found that IVF singletons had roughly double the odds of perinatal mortality and about 2.7 times the odds of very low birth weight.2PubMed. Perinatal outcomes in singletons following in vitro fertilization: a meta-analysis
These numbers sound alarming in relative terms, but consider the baseline. Preterm birth affects roughly 10 percent of all births in the United States. Even a near-doubling of that rate means the large majority of IVF singletons still arrive at term. The risk is real and worth monitoring, but it is not the norm.
How Multiple Pregnancies Skewed the Early Picture
For the first two decades of IVF, clinics routinely transferred two, three, or even more embryos to improve the chance of pregnancy. That strategy worked in the sense that pregnancy rates climbed, but it also produced a surge in twins and higher-order multiples. Twins are far more likely to be born early and underweight regardless of how they were conceived, and much of the early association between IVF and poor birth outcomes was driven by this multiple-pregnancy problem rather than by IVF itself.
The fix has been a widespread shift toward transferring a single embryo. Research has consistently shown that elective single embryo transfer cuts the twin rate dramatically without sacrificing overall pregnancy rates when patients are selected carefully.3PubMed. Single embryo transfer – state of the art A more recent study found that single morula transfer cut preterm delivery rates to under 10 percent, compared to over 21 percent with double embryo transfer.4PubMed Central. Elective single morula transfer achieved better clinical outcomes than two cleavage embryos transfer in fresh IVF-ET cycles In many countries, single embryo transfer is now standard practice, and twin rates from IVF have plummeted as a result. That has narrowed the gap between IVF and natural-conception outcomes considerably, though, as the meta-analyses above show, it hasn’t eliminated it entirely for singletons.
Birth Defects
Several large studies have examined whether IVF-conceived children have higher rates of congenital anomalies. A meta-analysis pooling data from multiple studies found that children conceived through assisted reproduction had about a 22 percent higher likelihood of birth defects overall, with heart defects showing one of the larger increases.5PubMed Central. Risk of birth defects in children conceived with assisted reproductive technology: A meta-analysis A large Australian study published in the New England Journal of Medicine found that the unadjusted odds ratio for any birth defect with assisted conception was about 1.47, but after adjusting for parental factors, the risk for standard IVF dropped to 1.07 and was no longer statistically significant. ICSI, the technique where a single sperm is injected directly into the egg, carried a higher adjusted risk of about 1.57. Critically, the study also found that a history of infertility itself was associated with birth defects, even in couples who conceived without treatment.6PubMed. Reproductive Technologies and the Risk of Birth Defects
Some lab-related choices also appear to matter. One retrospective study found that transferring embryos at the earlier cleavage stage (day 3) and using fresh rather than frozen embryos were each independently associated with higher odds of malformations, while the specific type of fertilization (standard IVF versus ICSI) did not significantly influence the rate.7PubMed Central. Risk Factors for Prematurity and Congenital Malformations in Assisted Reproductive Technology Pregnancies-A Retrospective Study These findings hint that not all IVF cycles carry the same level of risk, and that specific technical decisions in the lab may matter as much as whether IVF was used at all.
Separating the Procedure from the Infertility
One of the hardest questions in this field is whether the health differences seen in IVF children come from the IVF process or from the underlying reason the parents needed IVF in the first place. Infertile couples may carry genetic or physiological factors that affect pregnancy outcomes regardless of how conception occurs. Sibling studies are one of the best tools for answering this, because they compare children born to the same mother through IVF and through unassisted conception, effectively controlling for many parental factors.
A sibling comparison study found that IVF-conceived singletons were still more likely to be born preterm, weigh less at birth, and have major congenital anomalies than their naturally conceived siblings. Even after adjusting for maternal age, birth order, and other factors, IVF singletons had about 1.6 times the risk of preterm birth and roughly 1.9 times the risk of major anomalies compared to their unassisted siblings.8PubMed Central. Neonatal characteristics of children conceived with in vitro fertilization or intrauterine insemination compared with sibling births from unassisted conceptions Because the parents are the same in both pregnancies, this pattern suggests the IVF process itself contributes some additional risk beyond what infertility alone would predict. However, the Australian data mentioned above showed that infertility was independently associated with birth defects even without any treatment, so the truth likely involves both the procedure and the biology of infertility working in tandem.
Fresh Versus Frozen Transfers Have Different Risk Profiles
A common assumption is that freezing embryos and transferring them in a later cycle is either universally safer or universally riskier than a fresh transfer. The reality is more of a tradeoff. A large individual-participant meta-analysis of randomized trials found that a freeze-all strategy increased the risk of hypertensive disorders in the mother and produced larger-for-gestational-age babies at a higher rate, but reduced the risk of small-for-gestational-age babies compared to fresh transfer.9Human Reproduction. P-782 Obstetric and Neonatal Outcomes following Freeze-all vs Fresh Embryo Transfer Strategies: An Individual Participant Data Meta-Analysis of Randomised Trials (INFORM) A separate study pointed specifically to how the uterus is prepared for a frozen transfer as a key variable: cycles using artificial hormone protocols to build the uterine lining had more than double the risk of pre-eclampsia compared to fresh transfers.10PubMed Central. Higher risk of pre-eclampsia and other vascular disorders with artificial cycle for frozen-thawed embryo transfer compared to ovulatory cycle or to fresh embryo transfer following in vitro fertilization
The cancer data add another dimension. A Danish cohort study found that children born after frozen embryo transfer had a higher risk of childhood cancer, particularly leukemia, compared to both fresh-transfer children and naturally conceived children. The leukemia risk was roughly doubled.11PLoS Medicine. Cancer in children born after frozen-thawed embryo transfer: A cohort study Whether this reflects something about the freezing and thawing process, the hormonal environment during implantation, or confounding factors remains unclear. Either way, the lesson is that neither fresh nor frozen transfer is categorically “safer” across all outcomes.
Cardiovascular and Metabolic Signals
Some of the more intriguing data involve what happens to IVF children as they grow. A study of children aged six to ten found that those conceived through assisted reproduction had slightly higher systolic and diastolic blood pressure than naturally conceived peers, with the diastolic difference averaging about 5 mm Hg. The proportion with elevated blood pressure was also higher in the IVF group.12JAMA Network Open. Assessment of Cardiovascular Health of Children Ages 6 to 10 Years Conceived by Assisted Reproductive Technology A smaller study of IVF-conceived adolescents found thicker carotid artery walls and stiffer arteries compared to controls, though measures of overall vascular function did not differ significantly.13PubMed Central. Vascular Health of Children Conceived via In Vitro Fertilization A review summarizing longer-term follow-up data noted signals of raised blood pressure, elevated fasting glucose, and increased body fat in IVF offspring.14Human Reproduction Update. The longer-term health outcomes for children born as a result of IVF treatment: Part I–General health outcomes
These are small differences so far, and nobody knows yet whether they translate into actual cardiovascular disease later in life. The oldest IVF babies are only in their mid-forties, so long-term data simply don’t exist. But the consistency of the signal across multiple studies has made researchers pay attention, and it’s one reason why calls for long-term health registries tracking IVF offspring have grown louder.
Childhood Cancer
A meta-analysis of studies comparing children conceived through fertility treatment to naturally conceived children found a modest overall increase in cancer risk, with the strongest signals for blood cancers like leukemia and for rare liver tumors. There was no clear increase in neural tumors. The authors emphasized that the data cannot distinguish whether the elevated risk comes from the fertility treatment itself or from the subfertility that led to treatment.15PubMed Central. Cancer risk among children conceived by fertility treatment In absolute terms, childhood cancer remains rare in both groups. The relative increase, while statistically meaningful in large datasets, translates to a very small number of additional cases per thousand births.
Neurodevelopmental Outcomes
Research on whether IVF children are more likely to develop autism, cerebral palsy, or intellectual disability has produced mixed results. One systematic review found that ART-conceived children overall had about 1.8 times the risk of cerebral palsy compared to naturally conceived children. When looking specifically at the type of fertilization, ICSI-conceived children had higher risks of intellectual disability and autism compared to those conceived by conventional IVF.16PubMed Central. Risk of neurodevelopmental disorders in children born from different ART treatments: a systematic review and meta-analysis A more recent meta-analysis focusing on differences between ICSI and conventional IVF confirmed that ICSI was associated with a higher incidence of autism, but found no significant difference between the two techniques for ADHD, intellectual disability, or cerebral palsy. Whether embryos were transferred fresh or frozen did not appear to affect neurodevelopmental outcomes.17PubMed Central. Does the risk of neurodevelopment disorders in children differ with different ART treatments? A systematic review and meta-analysis
A prospective study directly comparing developmental scores between ICSI and conventional IVF children found no significant difference in the proportion with abnormal developmental screening scores, suggesting that whatever excess risk exists may be concentrated in severe cases or confounded by factors like prematurity that are more common in IVF births generally.18Human Reproduction. Developmental outcomes of children born through ICSI versus conventional IVF (cIVF) in couples with non-male factor infertility
Allergies and Immune-Related Conditions
Older studies found no meaningful difference in asthma, allergic rhinitis, or eczema rates between IVF and naturally conceived children.19Allergologia et Immunopathologia. Prevalence of asthma and other allergic diseases in children born after in vitro fertilisation More recent and larger studies tell a more nuanced story. A large population-based study found that ART-conceived children had a modestly increased likelihood of developing asthma, allergic rhinitis, and atopic dermatitis, though the absolute increases were small.20PubMed Central. Atopic Disease Development in Offspring Conceived via Assisted Reproductive Technology A separate study specifically looking at frozen embryo transfer found a much higher prevalence of food allergy and food allergen sensitization in the FET group compared to naturally conceived children, though rates of asthma and eczema were not significantly different between the groups.21Reproductive BioMedicine Online. Association between frozen embryo transfer and childhood allergy: a retrospective cohort study
The food allergy finding is particularly interesting because it echoes broader concerns about epigenetic changes during embryo freezing and thawing. But it comes from a single retrospective study, and food allergy prevalence is notoriously difficult to measure consistently. This is an area where the evidence is still taking shape.
Placental Complications
IVF pregnancies carry elevated rates of placental problems that directly affect both mother and baby. A large Chinese study of hospitalized births found that IVF pregnancies had roughly double the rate of placenta previa, placenta accreta, and abnormal placental shape compared to non-IVF pregnancies, even after adjusting for maternal age and pre-existing conditions.22PubMed Central. Placental Abnormalities and Placenta-Related Complications Following In-Vitro Fertilization: Based on National Hospitalized Data in China A case-control study found that women who conceived through ART were nearly four times more likely to develop placenta previa.23PubMed Central. Risk Factors Associated With Placenta Previa: A Matched Case-Control Study When endometriosis is in the mix, the risk climbs even further: among ART pregnancies delivered by cesarean, women with endometriosis had a placenta previa rate of 20 percent, compared to about 5.5 percent in ART patients without endometriosis.24PubMed. Endometriosis Increases the Risk of Placenta Previa in Both IVF Pregnancies and the General Obstetric Population
Placental problems matter for the baby because they can restrict blood supply, trigger preterm delivery, or cause dangerous bleeding. This is one pathway through which some of the excess preterm birth and low birth weight risk in IVF pregnancies may operate.
Growth, Puberty, and What Happens by School Age
The reassuring news is that most growth differences between IVF and naturally conceived children fade early. A national cohort study tracking children from birth to school entry found that by ages four to seven, weight, length, and body mass index in both fresh-transfer and frozen-transfer children were similar to those in naturally conceived children.25PubMed Central. The growth of assisted reproductive treatment-conceived children from birth to 5 years: a national cohort study Some research has flagged subtler hormonal differences: one study of IVF-conceived prepubertal children found higher levels of growth-stimulating hormones like IGF-I and a more favorable lipid profile compared to controls, along with lower BMI.26Fertility and Sterility. In vitro fertilization Growth and development of children born after in vitro fertilization Another study noted that IVF-conceived girls showed slightly advanced bone age and higher levels of certain adrenal hormones during puberty compared to controls.27Human Reproduction. Pubertal development in children and adolescents born after IVF and spontaneous conception
Whether these hormonal differences mean anything clinically over the long run is unknown. They may reflect subtle epigenetic effects of the IVF process, or they may be within the range of normal variation and ultimately inconsequential.
Epigenetics and Imprinting Disorders
One mechanism that researchers suspect could underlie some IVF-related health differences involves epigenetics, specifically changes in how genes are activated or silenced without altering the DNA sequence itself. The most concrete example is Beckwith-Wiedemann syndrome, a rare overgrowth disorder. An early prospective study found that ART-conceived children appeared to have the condition at several times the background rate, and molecular analysis showed that most of the affected children had specific epigenetic alterations at imprinting-control regions.28The American Journal of Human Genetics. Association of In Vitro Fertilization with Beckwith-Wiedemann Syndrome and Epigenetic Alterations of LIT1 and H19 This syndrome remains very rare even in IVF populations, but the finding opened a broader line of inquiry into whether the laboratory environment during the critical first days of embryo development can leave lasting epigenetic marks.
Related to this, research in animal models has found that details of the embryo culture environment, including which culture medium is used, can influence birth weight. A large study of human births confirmed that different commercial culture media produced measurably different birth-weight outcomes, with some media associated with higher rates of large-for-gestational-age babies.29Human Reproduction Open. Effects of different embryo culture media on birthweight following assisted reproductive technology A study using mouse models suggested that oxidative stress during embryo culture could shorten telomeres, the protective caps on chromosomes that are associated with cellular aging.30Nature Communications. Telomere length in offspring is determined by mitochondrial-nuclear communication at fertilization Optimizing culture conditions, particularly oxygen levels, may mitigate this effect, but the finding underscores how sensitive early embryo development is to its surroundings.
Ovarian Stimulation as an Independent Factor
IVF doesn’t just involve the embryo’s time in the lab. Before egg retrieval, the mother undergoes ovarian stimulation with hormones to produce multiple eggs. Mouse studies have shown that this stimulation alone, independent of embryo culture, can reduce fetal weight, alter placental structure, and impair both egg quality and uterine receptivity.31PubMed. The impact of ovarian stimulation on implantation and fetal development in mice Another mouse study found that ovarian stimulation disrupted the function of immune cells in the uterus that are involved in normal placental development.32PubMed Central. Ovarian Stimulation in Mice Resulted in Abnormal Placentation through Its Effects on Proliferation and Cytokine Production of Uterine NK Cells These are animal studies, and results don’t always translate directly to humans, but they suggest that part of the excess risk in IVF pregnancies may begin before the embryo is even created. The trend toward milder stimulation protocols in recent years is partly motivated by these concerns.
Reproductive Health of the First IVF Generation
Louise Brown, the first person born through IVF, turned 47 in 2025. The oldest IVF-conceived adults are now well into their reproductive years, which allows the first direct look at whether being conceived through IVF affects your own fertility. A study comparing IVF- and GIFT-conceived adults to non-ART controls found that similar proportions in both groups had already had children, and similar proportions had sought medical advice for fertility concerns. The only reproductive condition that trended higher in IVF-conceived women was endometriosis, reported by 16 percent compared to 8 percent of controls, though this difference did not reach conventional statistical significance. Male reproductive outcomes were similar between groups.33Fertility & Reproduction. Reproductive Health of Adults Conceived by IVF and GIFT
These early data are reassuring but limited. The sample sizes are still small, and IVF-conceived adults are only now entering the age range where many fertility and chronic health issues typically surface. The coming decade will be crucial for understanding whether the subtle cardiovascular, metabolic, and epigenetic signals observed in childhood amount to real clinical consequences in adulthood, or whether they are statistical echoes that fade with time.