Perinatal outcomes improving for ART infants

A Nordic study of more than 92,000 children shows that perinatal outcomes after use of assisted reproductive technology (ART) have improved considerably in the past 20 years. Those results, in large part, are due to a reduction in multiple births following introduction of single-embryo transfer.

Researchers analyzed perinatal outcomes of 62,379 ART singletons and 29,758 ART twins, who were born from 1988 to 2007 in 4 Nordic countries. The ART singletons were compared with a control group of 362,215 singletons who were spontaneously conceived. The ART twins were compared with all of the spontaneously conceived twins (n  = 122,763) who were born in the Nordic countries during the study period. Rates of adverse perinatal outcomes were stratified into 1988 – 1992, 1993 – 1997, 1998 – 2002, and 2003-2007 and presented according to multiplicity.

Point/Counterpoint: Placental examination

From 1998 to 2002, the proportion of twin deliveries as a result of ART remained stable at approximately 23%, but decreased gradually, to 11.6% in 2007.

Looking at trends in births, the adjusted odds ratio (aOR) for delivery <32 weeks declined from 3.80 (95% confidence interval [CI] 2.62 – 5.52) in 1988 to 1992 to aOR 2.06 (95% CI 1.82–2.33) in 2003 to 2007; for twins it declined from aOR 1.28 (95% CI 0.97 – 1.69) to aOR 1.12 (95% CI 0.86–1.46) over the same time period. Likelihood of very low birthweight (<1500 g) declined from aOR 4.77 (95% CI 3.25 – 7.01) to aOR 2.11(95% 1.85–2.41) for singleton deliveries, whereas in twins, the trend was from aOR 1.12 (95% 0.85 – 1.48) to aOR 0.82 (95% CI 0.72–0.94). Among singletons, the risk of being small for gestational age declined from aOR 1.83 (1.49 – 2.26) to aOR 1.13 (95% CI 1.05–1.22), compared with aOR 0.77 (95% CI 0.65 – 0.91) to aOR 0.76 (95% CI 0.71–0.82) in twins over the same time period.

The researchers characterized the decline in risk of being born preterm or very preterm in ART-conceived singletons as “dramatic” while noting that they were unable to adjust for potential confounders such as body mass index or length or cause of infertility.  “Our data,” they said, “underline the importance of lowering the national twin rates, also in regard to the health advantages in ART singletons.”

To get weekly advice for today's Ob/Gyn, subscribe to the Contemporary OB/GYN Special Delivery.