Menarcheal age and habitual miscarriage: evidence for an association.

Among women who habitually miscarried (two or more miscarriages) we observed a modest association for increased risk of miscarriage of first pregnancies in those with younger (especially less than or equal to 11 years) and older (greater than or equal to 16 years) menarcheal age (quadratic G2 = 3.49, P = 0.062). No associations of menarcheal age with first pregnancy miscarriage were observed when analysed by age at first pregnancy, or with pregnancy number among women with only one miscarriage. Unusually early or late menarcheal age appears to increase the risk of miscarriage of the first pregnancy but only among women who will go on to habitually miscarry.