Fecundity of daughters born after short, intermediate, or long birth intervals. An analysis of family reconstitutions from The Netherlands, late 19th-early 20th century.

In an historical cohort study, we compared the reproductive performances of women born after short (< 14 completed months), intermediate (21-32 completed months), and long (> 39 completed months) birth intervals. Of the initial study base, comprising family reconstitutions of 1,425 women born between 1873 and 1902 in or around Rotterdam (The Netherlands) and married before age 45, a large portion (data of 1,001 women born between 1888 and 1902) was uninformative because of (unintended) selection on birth control behavior. Among the remaining 424 women, those born after very short birth intervals (less than 1 year) showed higher likelihood of childlessness and stillbirth in the offspring than those born after intermediate intervals (adjusted odds ratios (OR) and 95%-confidence intervals: 7.7 [1.8-33.0] and 3.3 [1.3-8.3], respectively). The latter association, however, nearly disappeared after restriction to women whose preceding sibling lived at least 1 year. Women born after modestly short intervals (12-13 months) exhibited longer interpregnancy intervals. So did women born after long birth intervals, but this might well be attributable to intergenerational transmission of reproductive behavior. These results indicate that fecundability is reduced in women born after short birth intervals.