CONDITIONS AT CONCEPTION AND RISK OF MENSTRUAL DISORDERS

In a case-control study, we evaluated the association of the risk of m enstrual disorders with four periconceptional factors: short preceding interpregnancy interval (<6 months), low (less than or equal to 19 ye ars) or high (less than or equal to 40 years) maternal age at concepti on, and month of conception. We divided 919 women who had visited a fe rtility clinic between 1991 and 1995 into three categories: cases (wit h mean menstrual cycle length greater than or equal to 42 or less than or equal to 21 days, or a variation of greater than or equal to 14 da ys between cycles, or amenorrhea, N = 294), controls (with cycles with in a range of 25-35 days and variation less than or equal to 7 days, N = 520), and intermediates (N = 105). A self-administrable questionnai re mas mailed, asking for information about maternal reproductive hist ory and age, and potential confounders such as smoking, exercise, and level of education. Response (77%) differed little among cases, interm ediates, and controls. We found elevated risks for short pregnancy int ervals [adjusted odds ratio (OR) = 2.04; 95% confidence interval (CI) = 1.04-4.02] and advanced maternal age (OR = 3.24; 95% CI = 1.27-8.30) but not for low maternal age (OR = 0.58; 95% CI = 0.11-3.14) (cases v s controls). We found similar effects for intermediates vs controls. T he distribution of month of conception did not differ much from contro ls for both cases and intermediates. The results indicate that concept ion after short pregnancy intervals or at advanced maternal age increa ses the risk of menstrual disorders in daughters. The precise etiology is unclear, but it may lie in the quality of the oocyte at conception .