More reason to consider electing single embryo transfers (eSET):
Twins born as a result of assisted reproductive technology (ART) have worse outcomes than those conceived naturally, an Australian cohort study showed.ART twins had higher risks of preterm birth (OR before 33 weeks 2.5, 95% CI 1.6 to 3.7), low birth weight (OR below 1,500g 2.2, 95% CI 1.4 to 3.4), and perinatal death (OR 2.2, 95% CI 1.1 to 4.6), according to the online report in Human Reproduction.
Although the study did not address causes, Hansen offered offered possible explanations for the results. “The underlying causes of parental infertility and/or components of the ART procedure may be increasing the risks of adverse outcome,” she said. “And increased concern about children born after a long period of infertility may also be contributing to their increased risk of hospitalization.” Previous studies have shown that twins born as a result of ART (ART twins) have a higher risk of perinatal problems than singletons, according to the researchers, although this has been mostly attributed to complications from multiple births in general.
There is conflicting evidence, however, about the degree to which assisted reproduction contributes to these problems, they said. To explore the issue, the investigators looked at perinatal outcomes for all twins born in western Australia over a seven-year period. Overall, there were 700 ART twins and 4,097 spontaneously conceived twins.
ART procedures included in vitro fertilization (IVF), intracytoplasmic sperm injection of eggs, and gammete intrafallopian tube transfer.
To enhance the accuracy of the comparisons, Hansen and colleagues compared ART twins with 620 sets of nonidentical, naturally conceived twins. Compared with this group, ART twins were more likely to be born to older women who had not previously given birth.
The mothers of ART twins were more likely to be covered by private insurance (OR 3.9, 95% CI 2.8 to 5.3) and to live in upscale communities (OR 2.2, 95% CI 1.4 to 3.2).
ART twins had longer initial hospital stays at birth (12 versus 8 days) and they were 60% more likely to be admitted to the neonatal intensive care unit after adjusting for several potential confounders (OR 1.6, 95% CI 1.0 to 2.7).
ART twins were also more likely to be admitted to the hospital during the first three years of life, although the difference was only significant during the second year (OR 1.6, 95% CI 1.1 to 2.5).
“Although most of the increase in admission risk can be accounted for by known maternal and infant characteristics, there is still a residual risk, particularly in the second year of life,” the researchers said.