Your Pregnancy Matters

Part Two: Assisted reproductive technologies and fetal risk

Your Pregnancy Matters

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There are some risks to fetuses conceived via ART that women hoping to become pregnant should discuss with their doctor.

Last week, I reviewed five of the most common maternal risks associated with assisted reproductive technologies (ART). This week, I’m looking at the five important fetal risks associated with these fertility treatments.

As I mentioned in last Tuesday’s post, ART may be the best option for women who struggle with infertility. I know this firsthand because ART turned out to be absolutely the right choice for me. But there are risks associated with it that women hoping to become pregnant should understand.

Fetal risks associated with ART

1. Multiple gestation

Multifetal gestation, or becoming pregnant with more than one baby, is perhaps the most notable fetal risk resulting from the increased use of ART. In 2009, almost half of all infants born as a result of ART (41 percent) were from multifetal pregnancies compared with only 3.5 percent of infants among the general birth population.

Multiple pregnancy is consistently associated with an increased risk of adverse outcomes for fetuses and neonates, the most important being preterm birth and complications related to preterm birth.

In an effort to prevent these associated risks, most professional societies, including the American Society of Reproductive Medicine (ASRM), encourage the use of single-embryo transfer and appropriate patient counseling regarding the risks of multifetal gestations with use of these technologies.

2. Preterm birth and low birth weight (LBW)

Many studies have shown an increased risk of both preterm birth, defined as delivery before 37 weeks of gestation, and low birth weight (infant weight <2500 grams) in pregnancies conceived via ART.

Multiple large studies have suggested that ART is associated with up to a twofold increased risk of preterm birth and low birth weight. However, it appears that frozen-embryo transfers are associated with a decreased risk of preterm birth and LBW compared to pregnancies conceived via fresh-embryo transfer, which suggests that the environment within the uterus at the time of implantation plays an important role in the development of these complications.

3. Congenital anomalies

Women who undergo ART appear to be at increased risk of having a child with a congenital malformation as compared to fertile women who conceive naturally.

The baseline risk of congenital anomalies in the general population is 2 to 4 percent, and this is potentially increased by about one-third in women who undergo ART. This means the absolute risk of having a child with an anomaly remains low, even in ART pregnancies.

Studies have not shown a higher prevalence of chromosomal abnormalities, such as Down syndrome, in pregnancies conceived using reproductive technology.

4. Neurodevelopmental issues

Although studies on this subject have been small, ART does not appear to be a risk factor for adverse neurodevelopmental outcomes or growth abnormalities.

However, the various procedures do result in more multiple gestations, which are at high risk for preterm birth and low birth weight, both of which are important independent risk factors for neurodevelopmental sequelae.

5. Perinatal mortality

Stillbirth and neonatal mortality rates appear to be slightly increased in pregnancies conceived via ART. This finding is likely due to the increased risk of maternal obstetrical complications, preterm birth, low birth weight, and multiple gestations.

Know the risks to your baby

Be sure to talk with your doctor about your medical history and the risks involved with fertility treatments. It’s important to remember that ART, while it has its risks, might be the right choice for you to start a family.

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