In vitro fertilization (IVF) has enabled millions of individuals and couples to achieve parenthood worldwide since its introduction in 1978. As IVF has become more common, questions about its potential impact on the health of children conceived have also increased. One recurring concern among prospective parents is whether IVF procedures carry an elevated risk of birth defects. This article explores the current scientific understanding of this topic.
Comparing Birth Defect Rates
Studies comparing birth defect rates in children conceived via IVF versus those conceived naturally have yielded varying results, with some suggesting a slight increase in risk. For instance, one study found that 6.2% of IVF-conceived children had a major birth defect, compared to 4.4% in naturally conceived children. Another study observed birth defects in 9.0% of IVF infants compared to 6.6% in naturally conceived infants, even after controlling for maternal factors.
Despite these observations, the absolute risk of a major birth defect in IVF-conceived children remains low, with more than 90% of these children being completely healthy. Challenges in directly comparing these rates persist due to difficulties in isolating the effects of IVF from other contributing factors, such as underlying parental infertility. The general fertile population has an inherent risk of birth defects, typically ranging from 3% to 5%.
Specific Observed Associations
When examining specific types of birth defects, some studies have noted associations with IVF, including malformations of the circulatory system, musculoskeletal defects, and known birth defect syndromes. A study in California identified increased rates of malformations of the eye (0.3% vs. 0.2%), heart (5.0% vs. 3.0%), and genitourinary system (1.5% vs. 1.0%) in IVF infants compared to naturally conceived infants.
A rare growth disorder known as Beckwith-Wiedemann Syndrome (BWS) also appears more frequently in IVF babies, occurring in approximately 1 in 4,000 IVF babies compared to 1 in 14,000 to 35,000 spontaneously conceived babies. These observed associations signify a correlation, not necessarily a direct causation by the IVF procedure itself. Many of these findings represent small increases in overall rare conditions, and further research is needed to fully understand the underlying reasons for these connections.
Factors Beyond IVF Procedures
Several factors independent of the IVF procedure may contribute to any observed higher rates of birth defects. Advanced maternal age is a factor, as the risk of chromosomal abnormalities, such as Down syndrome, increases sharply after age 35. Similarly, advanced paternal age is associated with an increased likelihood of sperm DNA mutations, potentially raising the risk of birth defects and genetic disorders in offspring.
Underlying infertility in parents can also play a role, as the conditions causing infertility may independently contribute to a higher risk of birth defects, regardless of conception method. For example, men with severe sperm production defects may have a higher risk of chromosomal abnormalities that could be passed to their children. Lifestyle factors, such as alcohol consumption, can also impact fertility and potentially contribute to congenital abnormalities if pregnancy occurs.
Mitigating Risks and Patient Care
Medical professionals employ several strategies to assess and potentially reduce the risk of birth defects in IVF pregnancies. Preimplantation Genetic Testing (PGT) is a tool used during IVF to screen embryos for genetic abnormalities before transfer. PGT-A (for aneuploidy) identifies embryos with the correct number of chromosomes, which can reduce the risk of miscarriage and improve implantation success.
PGT-M (for monogenic diseases) can detect specific gene mutations that one or both parents are known to carry, helping to prevent the transmission of inherited disorders like cystic fibrosis or sickle cell anemia. After conception, standard prenatal screening and diagnostic tests are available to all pregnant individuals, including those who conceived via IVF. These include non-invasive prenatal testing (NIPT) to screen for chromosomal differences, ultrasound scans to assess fetal development and detect structural malformations, and diagnostic procedures like amniocentesis or chorionic villus sampling (CVS) for more definitive genetic analysis. Genetic counseling provides personalized guidance to prospective parents, helping them understand their individual risks and navigate available testing options to make informed decisions about their reproductive journey.