Early-life factors and adult anti-Müllerian hormone levels

Risk of major gynecologic surgery before age 40 among daughters of young mothers

STUDY QUESTION

Is being born of a young mother associated with worse gynecologic health, as indicated by a bilateral oophorectomy or hysterectomy before age 40?

SUMMARY ANSWER

Daughters of mothers younger than 25 did not have reduced parity but did have a higher risk of having bilateral oophorectomy or hysterectomy before age 40, particularly if their mother was younger than 20 years at their birth.

WHAT IS KNOWN ALREADY

Three recent studies have reported lower fecundability among daughters of mothers younger than 20 years; adverse socioeconomic conditions may explain part of that association.

STUDY DESIGN, SIZE, DURATION

This study reports cumulative, primarily retrospective, accrual of outcomes up to age 40 among 41 450 women recruited into the US-based Sister Study between 2003 and 2009.

PARTICIPANTS/MATERIALS, SETTING, METHODS

The analysis sample included women ≥41 years at the time of the latest follow-up and <66 years at recruitment. Using log-binomial regression, we estimated adjusted relative risks (RRs) of having major gynecologic surgery (bilateral oophorectomy or hysterectomy) before age 40 by age of the participant's mother (G1) when she gave birth to the participant (G2). All models were adjusted for father's age at G2's birth, daughter's self-identified race/ethnicity, and year of birth. We assessed possible effect modification by stratifying the analyses by self-reported G2's family income level during childhood (poor-low, medium-high) and G2's educational level (categorized as below bachelor's degree and bachelor's degree or higher) and, in the following step, by G2's age at first birth.

MAIN RESULTS AND THE ROLE OF CHANCE

Compared with daughters born to mothers aged 30-34, daughters of mothers <20 and 20-24 years had an RR of 1.74 (95% CI 1.51, 2.00) and 1.35 (1.22, 1.50), respectively, of major gynecologic surgery before age 40. Although lower childhood income, G2 education, and giving birth before age 25 were strongly associated with outcome risk, the RRs changed little after accounting for those factors.

LIMITATIONS, REASONS FOR CAUTION

This is a descriptive study of a proxy indicator of poor gynecologic health. Furthermore, all information was self-reported and, for nearly all women, recalled after the event. The measures used for socioeconomic status may have been insufficient.

WIDER IMPLICATIONS OF THE FINDINGS

Daughters of younger mothers did not have reduced parity but appeared to have a higher risk of major gynecologic surgery before age 40. This study adds to prior evidence that daughters of young mothers have worse gynecologic health.

STUDY FUNDING/COMPETING INTEREST(S)

This research was supported in part by the Intramural Research Program of the NIH, National Institute of Environmental Health Sciences (Z01-ES044005, Z01-ES102245, and Z01-ES103086). The authors report no conflict of interest.

TRIAL REGISTRATION NUMBER

N/A.

The Causal Evidence of Birth Weight and Female-Related Traits and Diseases: A Two-Sample Mendelian Randomization Analysis

Objectives: A large meta-analysis indicated a more pronounced association between lower birth weight (BW) and diseases in women but less concern about the causality between BW and female-related phenotypes and diseases.

Methods: Mendelian randomization (MR) analysis was used to estimate the causal relationship between two traits or diseases using summary datasets from genome-wide association studies. Exposure instrumental variables are variants that are strongly associated with traits and are tested using four different statistical methods, including the inverse variance weighting, MR-Egger, weighted median, and weighted mode in MR analysis. Next, sensitivity analysis and horizontal pleiotropy were assessed using leave-one-out and MR-PRESSO packages.

Results: The body mass index (BMI) in adulthood was determined by BW (corrected β = 0.071, p = 3.19E-03). Lower BW could decrease the adult sex hormone-binding globulin (SHBG) level (β = −0.081, p = 2.08E-06), but it resulted in increased levels of bioavailable testosterone (bio-T) (β = 0.105, p = 1.25E-05). A potential inverse effect was observed between BW and menarche (corrected β = −0.048, p = 4.75E-03), and no causal association was confirmed between BW and the risk of endometriosis, leiomyoma, and polycystic ovary syndrome.

Conclusion: Our results suggest that BW may play an important role and demonstrates a significant direct influence on female BMI, SHBG and bio-T levels, and menarche.