ART Outcomes Mostly Better for Lesbian vs Heterosexual Couples

Lesbian couples who conceived via assisted reproductive technology (ART) had significantly better or comparable birth outcomes to heterosexual couples who conceived naturally or via ART, a new analysis of Swedish births showed.

Among all births in Sweden from 2007 to 2018, babies of heterosexual couples who conceived naturally or via ART had a mean birth weight of 3429.5 g and 3342.9 g, respectively, compared with 3460.2 g for babies of the same-sex couples who conceived via ART (both P<0.001), reported Alice Goisis, PhD, of University College London, and co-authors in a research letter published in JAMA.

In addition, babies of the same-sex lesbian couples who conceived via ART had a mean gestational age of 278.1 days versus 277.6 days for babies of heterosexual couples who conceived naturally (P=0.004) and 274.7 days for those whose parents conceived via ART (P<0.001).

"Higher rates of adverse birth outcomes have been consistently reported among children conceived via assisted reproductive technology compared with children conceived through natural conception," Goisis and team wrote, noting that higher rates of multiple births in ART pregnancies may partially explain the increased risk.

"It remains unclear to what extent the remaining difference can be attributed to the reproductive technology or to factors related to infertility, which is associated with an elevated risk of poorer birth outcomes," they added. "Same-sex lesbian couples undergo ART treatments generally without experiencing infertility."

The authors also found that proportions of low birth weight and preterm birth were higher in ART conceptions among heterosexual couples compared with the lesbian couples, but this did not reach statistical significance.

"The findings suggest that it's not the treatment per se that is associated with poor birth outcome, but other factors," Goisis told MedPage Today.

She also pointed out that in other contexts -- especially places where ART is less accessible, particularly for same-sex lesbian couples -- the stress of accessing treatment could potentially result in worse birth outcomes.

In Sweden, lesbian couples have been eligible to receive publicly funded ART treatments with donated sperm since 2005, which gave Goisis and co-authors substantial data to work with.

More research in other countries is needed to determine if results would be similar, Goisis added.

She and her team used the Swedish National Quality Registry for Assisted Reproduction, which includes all ART treatments -- in vitro fertilization, intracytoplasmic sperm injection, and intrauterine insemination -- and linked to the medical birth register and the total population registers, which include data on birth outcomes and sociodemographic characteristics.

From 2007 to 2018, there were 868 ART births among lesbian couples, 23,488 ART births among heterosexual couples, and 456,898 natural births.

Mean maternal age at birth was 32.9 among the lesbian couples, 33.2 among heterosexual couples who used ART, and 28.3 among couples who had natural births. Both same-sex and heterosexual couples who conceived with ART had a higher proportion of multiplicity (5.8% and 7.5%, respectively) compared with natural births (2.1%).

Goisis and colleagues focused on first live births and assessed four outcomes: birth weight, gestational age, low birth weight (<2,500 g), and preterm delivery (<37 weeks of gestation).

They noted that the presence of infertility factors was not directly assessed, which was a limitation to their study. In addition, the sample size of the lesbian couples was relatively small and reduced the statistical power of the study.

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