Lasquety, M. G., Rodriguez, D., & Fehring, R. J. (2012). The Influence of BMI Levels on Phases of the Menstrual Cycle and Presumed Ovulation. The Linacre Quarterly, 79(4), 451-459. https://doi.org/10.1179/002436312804827082
Lasquety MG, Rodriguez D, Fehring RJ. The Influence of BMI Levels on Phases of the Menstrual Cycle and Presumed Ovulation. Linacre Q. 2012;79(4):451-459. doi:10.1179/002436312804827082
Lasquety, Mary Grace, et al. "The Influence of BMI Levels on Phases of the Menstrual Cycle and Presumed Ovulation." The Linacre Quarterly, vol. 79, no. 4, 2012, pp. 451-459.
Cycles of overweight and obese women more often lacked an LH surge
Overweight and obese women were 34 percent less likely to show a detected LH surge, the urine signal that ovulation is near. The finding comes from a registry of 244 self-selected Milwaukee women who charted 2,035 cycles with a fertility monitor. Luteal phase length also differed between groups, by less than a day.
Key Findings
Cycles with no detected LH surge: 9.4 percent in normal weight women, 10.3 percent in overweight women and 20.4 percent in obese women.
Combined overweight and obese women had no recorded LH surge in 13.5 percent of cycles. Odds ratio 0.66 (95 percent CI = 0.48–0.92).
Luteal phase length differed among the three groups (F = 4.62, p < 0.01). Normal weight women differed from both other groups (p < 0.01).
Length of menses differed among groups (F = 3.03, p < 0.05). Cycle length and follicular phase length showed no significant differences.
Of 244 participants, 141 had normal weight, 67 were overweight and 36 were obese. Overweight or obese women made up 42 percent (103/244).
Interpretation
This retrospective analysis of self-selected women who charted for their own reasons shows association only. A missing LH surge may reflect anovulation. Serial ultrasound could have confirmed it but was not done, and afternoon surges or testing errors could also explain missed surges. The luteal phase gap was under a day, which the authors call small clinically. The overweight and obese groups were older with more pregnancies, which may have influenced results. The authors add that most obese women ovulate normally.
RRM Context
Restorative reproductive medicine looks for the cause of infertility, and ovulatory function is one place it looks. Fertility awareness charting shows cycle patterns over months that a single visit cannot. An LH surge marks an ovulatory event. Serial ultrasound is the tool that confirms an egg was released.
Our editorial summary of this paper, not the article's abstract.
Abstract
Obesity and high body mass index (BMI) are known to be risks for anovulation and infertility. Little is known about how BMI levels affect parameters of the menstrual cycle. The purpose of this study was to determine the influence of BMI on parameters of the menstrual cycle and the likelihood for ovulation. The participants in this study were 244 women between the ages of twenty and fifty-four (mean thirty years) who charted from one to thirty-six menstrual cycles (mean seven cycles) for a total of 2,035 cycles. Urinary luteinizing hormone (LH) threshold tests were used to estimate the day of ovulation and the lengths of the follicular and luteal phases. The 244 participants were classified as normal weight with a BMI of 18.5-24.9 kg/m2 (N = 141), overweight with a BMI of 25-29.9 kg/m2 (N = 67), and obese with a BMI of 30 kg/m2 or greater (N = 36). One-way ANOVA indicated that there was a significant difference between groups in length of the luteal phase (F = 4.62, p < 0.01) and length of menses (F = 3.03, p < 0.05). Odds ratio indicated that the combined obese and overweight group was 34 percent less likely to have a positive detected urinary LH surge. We concluded that obesity might contribute to infertility by shortening the luteal phase and decreasing the probability of ovulatory menstrual cycles.
