Body mass index matters little in success of intrauterine insemination

Women who are overweight or obese do not necessarily have lower chances of a successful birth following infertility treatments, including intrauterine insemination, relative to women with normal weight, a study has found.

The analysis was based on 3,217 IUI treatment cycles in 1,306 patients (mean age, 32 years; mean body mass index [BMI], 27.5 kg/m²). Forty-seven percent of the cycles were in normal weight women, 24.1 percent in overweight women, and 28.3 percent in obese women (mean BMI, 37.3 kg/m²). The total motile sperm in the inseminate was similar across the BMI groups.

Most treatments were indicated for unexplained infertility (30 percent), while others were for male factor infertility (19 percent) or anovulation (16 percent). Anovulation was common in the obese group (25 percent). Oral ovulation induction was used in the majority of cycles (61 percent), unmedicated IUI in 14 percent, and injectable ovulation induction in 23 percent.

Live birth rates were similar between normal weight and obese women (10 percent vs 11 percent; adjusted odds ratio [aOR], 1.02, 95 percent confidence interval [CI], 0.76–1.37). When analysing BMI as a continuous variable, each unit increase in BMI had a null effect on birth success (aOR, 1.00, 95 percent CI, 0.984–1.019; p=0.906). There also was no difference in rates of clinical pregnancy, multiple gestation, or multiple delivery.

However, a BMI ≥30 kg/m² was associated with a higher likelihood of biochemical pregnancy compared with a BMI in the normal range (aOR, 2.37, 95 percent CI, 1.33–4.25). Neither miscarriage nor an ectopic pregnancy was more likely to occur in the obese group.