BMI in Both Partners Affects Fertility and Miscarriage Risk

TOPLINE:

Higher body mass index (BMI) in both partners is linked to lower fecundability and increased subfertility. Overweight and obesity in women are associated with higher odds of miscarriage.

METHODOLOGY:

• Researchers conducted a population-based prospective cohort study in Rotterdam, the Netherlands, from August 9, 2017, to July 1, 2021.
• A total of 3604 women and their partners were included, with follow-up until birth.
• BMI was measured in preconception or early pregnancy, and outcomes included fecundability, subfertility, and miscarriage.
• Fecundability was defined as the probability of conceiving within 1 month, and subfertility as time to pregnancy or duration of actively pursuing pregnancy of more than 12 months or use of assisted reproductive technology.
• Miscarriage was defined as pregnancy loss before 22 weeks of gestation.

TAKEAWAY:

• Higher BMI in women and men was associated with lower fecundability: for every unit increase in BMI, fecundability decreased (women, 0.98; 95% CI, 0.97-0.99; men, 0.99; 95% CI, 0.98-1.00).
• Women with overweight (0.88; 95% CI, 0.80-0.98) and obesity (0.72; 95% CI, 0.63-0.82) had lower fecundability than women with normal weight.
• Overweight (1.35; 95% CI, 1.11-1.63) and obesity (1.67; 95% CI, 1.30-2.13) in women were associated with increased odds of subfertility.
• Obesity in men was associated with increased odds of subfertility (1.69; 95% CI, 1.24-2.31).

IN PRACTICE:

“We observed in this cohort study that BMI outside of the normal category in women and men was associated with lower fecundability, subfertility, and increased odds of miscarriage. Optimizing BMI from the preconception period onward in women and men might be an important strategy to improve fertility and pregnancy outcomes,” wrote the authors of the study.

SOURCE:

The study was led by Aline J. Boxem, MD, and Vincent W. V. Jaddoe, MD, PhD, The Generation R Study Group, Erasmus University Medical Centre in Rotterdam, the Netherlands. It was published online on September 19, in JAMA Network Open.

LIMITATIONS:

The study’s generalizability may be affected by differences between included and excluded participants, who were younger and had a higher BMI. The accuracy of time-to-pregnancy duration may have been impacted by retrospectively answered questionnaires. Residual confounding might still be an issue due to the observational nature of the study.

DISCLOSURES:

Aline J. Boxem, MD, and Vincent W. V. Jaddoe, MD, PhD, disclosed receiving grants from the Erasmus University Medical Centre Rotterdam, the Erasmus University Rotterdam, and the Netherlands Organisation for Health Research and Development. Additional disclosures are noted in the original article.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.