Association between maternal age at menarche and newborn size

The impact of maternal age at menarche on newborn size was tested using dat a from 4,996 single births taking place at Vienna, Austria, between 1985 an d 1995-so-called teenager pregnancies were excluded from the present analys es. Ali women experienced pregnancies between the ages of 19 to 42 years. M aturational time was related significantly to infant weight and length inde pendent of maternal age and behavioral variables such as smoking. Early mat uration, i.e., age at menarche before the 12th birthday, was significantly associated with decreased newborn weight and size. The incidence of low-wei ght newborns was significantly higher in early-maturing mothers. The more f avorable nutritional status of women whose menarche occurred relatively ear ly was not able to compensate for the negative effects of early maturation on intrauterine growth. Higher circulating estrogen levels in early maturer s preserved into adulthood are discussed as possible reasons for intrauteri ne growth retardation of the offspring of early-maturing mothers.