Using data from the Swedish Medical Birth Registry, we examined whether reproductive history influenced pregnancy outcomes among women aged 30 to 39 years who gave birth to a first or second child in 1976 through 1980. They were classified group 1, primigravida; group 2, gravida 2, para 0; and group 3, gravida 2, para 1. Compared with women aged 20 through 24 years with the same parity and gravidity, the relative risk (RR) of late fetal deaths was significantly greater among those aged 35 through 39 years (RR: group 1 = 1.76, group 2=2.22, and group 3=2.39). The risk of giving birth to newborns who were low birth weight and preterm, or low birth weight at term, or 2,500 g or greater but preterm was greater among women aged 30 through 39 years in groups 1 and 2—significantly so for group 1 aged 30 through 39 years v group 1 aged 20 through 24 years. Risk increased with maternal age, from 30 through 34 to 35 through 39 years. The increased risk with age and parity-gravidity has ramifications for the increasing rate of delayed childbearing in the United States and elsewhere.
Forman MR, Meirik O, Berendes HW. Delayed Childbearing in Sweden. JAMA. 1984;252(22):3135–3139. doi:10.1001/jama.1984.03350220041028