Fertility is not altered in young adults born small for gestational age

The intrauterine environment may have a lifelong impact on individuals' health. However, results on the relationship between birth size and gonadal function are conflicting, and it remains unknown whether reproductive function is altered in adults born small for gestational age (SGA). The aim of the present study was to compare the fertility of young adults from the general population, born either SGA or appropriate for gestational age (AGA).

There were 579 adults born SGA (birthweight under the 10th percentile) who were compared with 703 subjects of the same age (age 29.4 +/- 4.1 years) born AGA (birthweight between 25th and 75th percentiles). They fulfilled a questionnaire focusing on the first attempt to give birth, to have a measure of the time to pregnancy and an estimation of the fecundability (the monthly pregnancy probability), two relevant indicators of fertility at the couple level. Ratios of fecundability between AGA and SGA subjects were adjusted for known fertility factors (age, smoking, reproductive history) and for socioeconomic status.

Time to pregnancy was comparable in the two groups: 5.7 +/- 8.0 versus 6.6 +/- 10.5 months in AGA and SGA, respectively (P = 0.31), in women and 5.1 +/- 7 versus 6.0 +/- 9 months in AGA and SGA, respectively, in men (P = 0.53). The adjusted ratios of fecundability comparing SGA to AGA subjects were not significant: HR = 0.91 [0.68;1.21] (P = 0.5) in women and HR = 0.95 [0.67;1.74] (P = 0.82) in men.

When studied in young adults from the general population, fertility is not reduced in those born SGA.