Do Fertility Treatments Increase Risk of Birth Injuries?

For couples struggling with infertility, assisted reproductive technology represents hope after months or years of disappointment. In vitro fertilization and other fertility treatments have enabled millions of people to become parents who otherwise couldn’t. These technologies are genuinely life-changing, creating families that wouldn’t exist without them. But like any medical intervention, they come with risks that deserve honest discussion.

The evidence is clear: yes, fertility treatments do increase the risk of certain birth injuries and complications compared to natural conception. Babies conceived through IVF and other assisted reproductive technologies have approximately double the risk of preterm birth, nearly double the risk of low birth weight, and elevated risks of cerebral palsy and other serious complications. These increased risks exist even in singleton pregnancies, though they’re dramatically higher in multiples.

Understanding these risks isn’t about discouraging people from pursuing fertility treatment. It’s about ensuring informed consent, encouraging practices that minimize risk like single embryo transfer, and preparing families for potential complications. The vast majority of babies conceived through fertility treatments are born healthy. But the elevated risks are real, measurable, and important for families to understand as they navigate fertility treatment decisions.

What Fertility Treatments and Assisted Reproductive Technology Include

The term “fertility treatments” encompasses various approaches to helping people conceive, with different risk profiles depending on the specific intervention.

The Range of Fertility Interventions

Fertility treatments range from relatively simple interventions to complex assisted reproductive technologies:

Ovulation induction with medications like clomiphene or letrozole stimulates egg production in women who don’t ovulate regularly. Intrauterine insemination places prepared sperm directly into the uterus around ovulation. In vitro fertilization involves retrieving eggs, fertilizing them with sperm in a laboratory, and transferring resulting embryos to the uterus. Intracytoplasmic sperm injection injects a single sperm directly into an egg, used with IVF for male factor infertility.

More complex variations include preimplantation genetic testing screening embryos for chromosomal abnormalities before transfer, and egg or sperm donation when one partner’s gametes aren’t viable.

How IVF Works and Why It Carries Different Risks

IVF, the most common form of ART, involves multiple steps:

• Ovarian stimulation with hormone injections produces multiple mature eggs
• Egg retrieval surgically removes eggs from ovaries
• Fertilization in the laboratory creates embryos
• Embryo culture allows development for several days
• Embryo transfer places one or more embryos into the uterus
• Remaining embryos may be frozen for future use

Each step potentially affects pregnancy outcomes. Hormonal stimulation affects the uterine environment. Laboratory culture occurs under conditions different from natural fertilization. The process of transferring embryos into the uterus differs from natural implantation.

The Critical Difference Between Singleton and Multiple Pregnancies

The single most important factor affecting birth injury risk in fertility treatments is whether the pregnancy is singleton or multiples. Historically, fertility clinics transferred multiple embryos to increase success rates, inadvertently creating high rates of twin and triplet pregnancies.

Multiple pregnancies carry dramatically elevated risks compared to singletons:

• Approximately 60% of twins and 90% of triplets are born preterm
• Low birth weight affects the majority of multiples
• Cerebral palsy risk is 4 to 6 times higher in twins, 15 times higher in triplets
• Neonatal mortality is substantially elevated
• Maternal complications including preeclampsia are much more common

Modern fertility practice increasingly emphasizes single embryo transfer to avoid these risks while maintaining acceptable pregnancy rates.

The Direct Evidence Linking Fertility Treatments to Increased Birth Injury Risk

Research consistently demonstrates elevated risks for babies conceived through fertility treatments, with data from CDC, ACOG, and international studies showing similar patterns.

Preterm Birth Rates in ART Pregnancies

Preterm birth, delivery before 37 weeks, occurs at approximately double the rate in ART pregnancies compared to natural conception. CDC data shows odds ratio of 2.0, meaning twice the risk.

For singleton ART pregnancies:

• Approximately 12% to 15% deliver preterm compared to 7% to 8% of naturally conceived singletons
• Very preterm birth before 32 weeks also occurs at elevated rates
• The increase persists even after controlling for maternal age and other factors

For multiple ART pregnancies, preterm birth rates exceed 50%, creating the compounded risks of both ART conception and multiple gestation.

Preterm birth is the single greatest risk factor for birth injuries including cerebral palsy, brain hemorrhage, and respiratory complications.

Low Birth Weight and Growth Restriction

Low birth weight, defined as less than 2,500 grams or about 5.5 pounds, occurs at 1.8 times the rate in ART pregnancies. This increased risk exists even for full-term babies, suggesting something about ART affects fetal growth beyond just increasing preterm birth.

Potential mechanisms include:

• Altered placental development from hormonal stimulation
• Underlying maternal factors affecting both fertility and fetal growth
• Epigenetic changes from laboratory culture conditions
• Increased rates of placental insufficiency

Low birth weight contributes to both immediate neonatal complications and long-term developmental problems.

Birth Defects and Congenital Anomalies

Birth defect rates are modestly elevated in ART pregnancies, with studies showing:

• Overall birth defect rate of approximately 4.3% in IVF vs 2.9% in natural conception
• Odds ratios ranging from 1.4 to 2.0 depending on the specific defect
• Cardiovascular defects showing particular increase
• Musculoskeletal abnormalities also elevated

Most defects are minor and treatable, but some are severe and life-altering. The increase isn’t dramatic but is statistically significant and consistent across studies.

Cerebral Palsy Risk Elevation

Perhaps most concerning, cerebral palsy rates are substantially higher in children conceived through ART. Studies show odds ratios ranging from 1.8 to 2.8, meaning nearly 2 to 3 times the baseline risk.

This increase primarily reflects the elevated preterm birth rate, as prematurity is the strongest risk factor for CP. However, some studies suggest slightly elevated CP risk in ART children even at term, pointing to additional mechanisms beyond just prematurity.

The absolute risk remains relatively low, with CP affecting approximately 0.3% to 0.5% of ART children compared to 0.15% to 0.2% of naturally conceived children. But for affected families, the distinction between natural and ART-related CP matters little.

Perinatal Mortality Rates

Stillbirth and neonatal death combined, called perinatal mortality, occur at 2.2 times the rate in ART pregnancies according to CDC data. This dramatic increase reflects:

• Higher rates of extreme prematurity
• Growth restriction and placental insufficiency
• Congenital anomalies incompatible with life
• Complications of multiple pregnancy when multiples result

Improvements in fertility practice, particularly single embryo transfer policies, are reducing but haven’t eliminated this excess mortality.

Why Fertility Treatments Increase Birth Complication Risks

Understanding the mechanisms behind increased risks helps distinguish what’s potentially modifiable from what’s inherent to fertility treatments or underlying infertility.

The Role of Multiple Embryo Transfer

Historically, the biggest driver of excess birth injury risk in fertility treatments was multiple embryo transfer. Transferring two, three, or even more embryos increased pregnancy rates but created high rates of twins and triplets.

The mathematics are stark:

• Approximately 30% of two-embryo transfers result in twin pregnancy
• Twin pregnancy carries 4 to 6 times the CP risk of singletons
• Nearly all excess morbidity and mortality in historical ART cohorts came from multiples

Recognition of this problem has driven the shift toward elective single embryo transfer (eSET). Modern pregnancy rates with eSET approach those with multiple embryo transfer in good prognosis patients, while dramatically reducing multiple pregnancy rates and associated complications.

Underlying Maternal Factors Contributing to Risk

Women requiring fertility treatment often have characteristics independently associated with pregnancy complications:

• Advanced maternal age, with women over 35 having higher baseline complication rates
• PCOS, endometriosis, and other conditions affecting fertility and pregnancy
• Prior pregnancy losses suggesting underlying issues
• Medical conditions like diabetes or thyroid disease affecting both fertility and pregnancy

Disentangling how much excess risk comes from ART itself versus underlying maternal factors is challenging. Studies controlling for maternal characteristics still show elevated ART risks, but the increase is smaller than crude comparisons suggest.

Hormonal Stimulation Effects on the Uterine Environment

The high-dose hormones used for ovarian stimulation create a uterine environment different from natural cycles:

• Supraphysiologic estrogen and progesterone levels
• Altered endometrial receptivity and gene expression
• Potential effects on early placental development
• Changes in uterine blood flow and inflammation

These alterations may impair implantation, placental function, and fetal growth, contributing to adverse outcomes even in singleton pregnancies.

Laboratory Culture and Epigenetic Effects

Embryos developing in laboratory culture dishes experience conditions different from natural development in the fallopian tube:

• Different oxygen tensions
• Artificial culture media
• Temperature and light exposure
• Handling and manipulation

Some research suggests these conditions may cause epigenetic changes, alterations in gene expression without changing DNA sequence itself. Whether these changes contribute meaningfully to birth injury risk remains unclear, but it’s an active area of investigation.

Placental Abnormalities in ART Pregnancies

ART pregnancies show higher rates of placental complications:

• Placenta previa, where placenta covers the cervix
• Placental abruption, premature separation
• Placental insufficiency affecting fetal growth
• Abnormal placentation patterns

These placental problems likely reflect altered implantation in the hormonally manipulated uterine environment. They contribute directly to preterm birth, growth restriction, and pregnancy loss.

Specific Birth Injuries More Common in Fertility Treatment Pregnancies

Understanding which specific injuries show elevated rates in ART pregnancies helps families and medical teams anticipate and monitor for complications.

Preterm Birth Complications Including Brain Hemorrhage

The doubled preterm birth rate in ART pregnancies translates directly to increased rates of prematurity complications:

Intraventricular hemorrhage, bleeding into brain ventricles, affects 20% to 30% of babies born before 28 weeks. The elevated preterm birth rate in ART pregnancies means more babies at risk. Periventricular leukomalacia, white matter brain damage, similarly affects premature babies and contributes to cerebral palsy risk.

These brain injuries occur more frequently in ART babies not because ART directly causes them, but because ART increases the likelihood of premature birth when these injuries occur.

Respiratory Distress and Chronic Lung Disease

Respiratory distress syndrome affects nearly all babies born very preterm, requiring mechanical ventilation and prolonged NICU stays. Chronic lung disease develops in many survivors of extreme prematurity requiring long-term oxygen and respiratory support.

The excess preterm birth in ART pregnancies means more families facing these respiratory complications and their long-term consequences.

Growth Restriction and Its Consequences

Babies from ART pregnancies show higher rates of small for gestational age, defined as birth weight below the 10th percentile for gestational age. This growth restriction increases risk of:

• Hypoglycemia after birth
• Difficulty maintaining temperature
• Polycythemia and jaundice
• Long-term metabolic and cardiovascular effects

Growth-restricted babies have elevated rates of cerebral palsy and developmental delays independent of gestational age at birth.

Congenital Heart Defects

Cardiovascular malformations occur at approximately 1.5 to 2 times the rate in ART pregnancies. While most heart defects are mild and treatable, severe defects requiring multiple surgeries or causing long-term disability do occur at elevated rates.

The mechanism isn’t fully understood but may relate to disrupted early cardiac development during critical windows coinciding with laboratory culture or altered maternal hormonal environment.

How Single Embryo Transfer Reduces Risk

The recognition that multiple pregnancy drives much of the excess risk in ART has led to dramatic changes in practice.

The Evidence Supporting Single Embryo Transfer

Studies comparing outcomes after single versus multiple embryo transfer show:

• Pregnancy rates with eSET in good prognosis patients approach those with double embryo transfer
• Twin rates drop from approximately 30% to under 2% with eSET
• Overall rates of preterm birth, low birth weight, and neonatal complications decrease substantially
• Cerebral palsy rates decline toward baseline
• Maternal complications also decrease dramatically

These benefits occur without meaningfully reducing the chance of taking home a baby, the ultimate success metric families care about.

Current Guidelines and Recommendations

Professional organizations including ASRM and SART now strongly recommend eSET in good prognosis patients:

• Women under 38 with good quality embryos
• Those with prior successful ART pregnancy
• Anyone desiring singleton pregnancy
• Patients with medical conditions where twin pregnancy would be particularly risky

Some countries legally restrict embryo transfer numbers, while in the U.S. the approach remains guideline-based rather than mandatory.

Why Some Clinics Still Transfer Multiple Embryos

Despite clear evidence and guidelines, multiple embryo transfer persists in some circumstances:

• Older patients or those with prior failures seeking to maximize pregnancy chance
• Financial pressures when patients pay out-of-pocket for limited cycles
• Clinic success rate reporting creating incentives to maximize pregnancy rates
• Patient preferences despite counseling about risks

Ongoing efforts focus on changing financial and regulatory structures to better align incentives with optimal medical practice.

Frozen Embryo Transfer and Risk Reduction

Some evidence suggests frozen embryo transfer cycles may have slightly better outcomes than fresh cycles:

• More physiologic hormone levels in frozen cycles
• Allows recovery from stimulation effects
• Enables preimplantation genetic testing
• Permits scheduling for optimal timing

Whether frozen transfer itself reduces risk or whether differences reflect patient selection remains debated, but the practice is increasingly common.

Prenatal Care and Monitoring for ART Pregnancies

Recognizing the elevated risks in ART pregnancies informs prenatal care strategies.

Enhanced Screening and Surveillance

ART pregnancies warrant closer monitoring:

• Earlier dating ultrasound to confirm singleton or multiple pregnancy
• More frequent growth assessments watching for restriction
• Screening for gestational diabetes, often earlier than standard timing
• Careful blood pressure monitoring for preeclampsia
• Consideration of specialized placental assessment if growth concerns arise

This enhanced surveillance aims to detect complications early when interventions might prevent adverse outcomes.

Timing and Mode of Delivery Considerations

Delivery planning for ART pregnancies considers:

• Increased cesarean section rates, partly due to maternal age and partly to clinician caution
• Timing of delivery, with some advocating for delivery by 39 weeks in uncomplicated singleton ART pregnancies
• Lower threshold for intervention if complications arise
• Preparation for potential NICU admission

The goal is balancing the risks of early delivery against the risks of waiting, individualized based on specific pregnancy factors.

Mental Health Support During High-Risk Pregnancy

The anxiety inherent in pregnancy after infertility, combined with awareness of elevated risks, creates significant emotional burden:

• Hypervigilance about every symptom
• Difficulty enjoying pregnancy due to fear
• Prior pregnancy losses intensifying anxiety
• Financial and emotional investment in this pregnancy

Mental health support, whether through counseling, support groups, or medication when appropriate, is often necessary for women managing high-risk ART pregnancy.

Balancing Risks Against the Benefits of Building a Family

Discussing ART risks requires acknowledging that for many families, the alternative to accepting these risks is never having children.

Putting Risk Increases in Perspective

While relative risk increases sound alarming, absolute risks often remain modest:

• CP risk increases from 0.15% to 0.3-0.4%, still affecting less than 1 in 200 ART babies
• Most birth defects are minor and treatable
• The majority of ART babies are born healthy at term
• Modern NICU care dramatically improves outcomes even for premature babies

These statistical realities don’t diminish the experience of families facing complications, but provide context for decision-making.

The Life-Changing Value of Fertility Treatment

For couples who couldn’t otherwise conceive, fertility treatment provides irreplaceable value:

• Creating families that wouldn’t exist without intervention
• Enabling genetic parenthood important to many people
• Providing hope and pathway to parenthood after years of infertility
• Allowing carrier screening and genetic testing options

These benefits clearly outweigh modest risk increases for most people pursuing ART.

Individual Risk Assessment and Counseling

Good fertility care involves individualized risk assessment:

• Discussing specific risks based on patient age, medical history, and planned treatment
• Counseling about single embryo transfer benefits
• Realistic expectations about pregnancy and delivery complications
• Shared decision-making about embryo transfer numbers and other treatment decisions

Informed consent requires honest discussion of risks, but presented in way that doesn’t unduly frighten or discourage people from pursuing appropriate treatment.

Questions to Ask Your Fertility Specialist About Birth Injury Risk

Families pursuing fertility treatment should feel empowered to ask direct questions about risks and risk reduction strategies.

Questions About Clinic-Specific Outcomes

• What are your success rates by age and diagnosis?
• What percentage of your pregnancies are multiples?
• What is your single embryo transfer rate?
• What are your preterm birth and low birth weight rates?

Quality clinics report these outcomes transparently and discuss them openly.

Questions About Your Specific Risk Factors

• Given my age and medical history, what are my specific risks?
• Do underlying conditions increase my risk of complications?
• Would single embryo transfer be appropriate for me?
• What monitoring and interventions might reduce my risks?

Questions About Practice Protocols

• What factors determine how many embryos you’ll recommend transferring?
• Do you have protocols for high-risk pregnancies?
• What prenatal monitoring is standard for ART pregnancies?
• Do you coordinate with high-risk obstetrics for pregnancy care?

Questions About Risk Mitigation

• What can I do to reduce birth injury risk?
• Would frozen embryo transfer be advantageous?
• Should I wait for additional testing before transfer?
• Are there lifestyle modifications that would help?

Moving Forward With Informed Decisions

Fertility treatments do increase the risk of birth injuries and complications, with CDC data showing approximately double the risk of preterm birth, 1.8 times the risk of low birth weight, 2.2 times the risk of perinatal mortality, and elevated cerebral palsy risk ranging from 1.8 to 2.8 times baseline. These increased risks reflect multiple factors including higher rates of multiple pregnancy when multiple embryos are transferred, effects of hormonal stimulation and laboratory culture on placental development and fetal growth, and underlying maternal factors that affect both fertility and pregnancy outcomes.

The single most important intervention reducing these risks is elective single embryo transfer, which dramatically decreases twin rates from approximately 30% to under 2% while maintaining acceptable pregnancy rates in appropriately selected patients. Professional guidelines from ASRM and SART now strongly recommend eSET for good prognosis patients, recognizing that the excess morbidity and mortality from multiple pregnancy far outweigh any modest benefit in per-cycle pregnancy rates.

For the millions of people who cannot conceive naturally, these elevated risks represent the realistic cost of building their families, risks that must be balanced against the profound benefit of becoming parents. The vast majority of ART babies are born healthy, and modern improvements in fertility practice including single embryo transfer policies and enhanced prenatal monitoring continue reducing the excess risks while maintaining the life-changing benefits of assisted reproductive technology. Understanding these risks enables informed decision-making and appropriate clinical management rather than deterring people from pursuing the family-building options they need.