Mother's age and daughter's fecundity. An epidemiological analysis of late 19th to early 20th century family reconstitutions.
BACKGROUND
At both ends of the female reproductive span, the risk of reproductive problems is increased. We hypothesize that this is partly explained by inadequate maturation of oocytes ('pre-ovulatory overripeness'). As this phenomenon has been shown to lead to gonadal anomalies in the offspring of animals, we tested the prediction that daughters of older and very young mothers more often suffer reproductive problems due to ovarian maldevelopment.


METHODS
We analysed family reconstitutions of 1907 women born in Rotterdam, the Netherlands, between 1873 and 1902. We defined several measures of fecundity based on numbers, birth rates and fates of offspring. We made use of general estimating equations (GEE), a statistical technique that allowed simultaneous analysis of different births per woman while controlling for various time-dependent or time-independent co-variables.


RESULTS
The results indicated an increased risk of childlessness (adjusted odds ratio (aOR = 2.6, 95% CI : 1.1-7.4), stillbirth (aOR = 2.5, 95% CI : 1.1-5.6) and multiple birth (aOR = 2.1, 95% CI : 0.8-5.4) for daughters of mothers of >or=40 years as compared to daughters born to mothers of intermediate age (24-30 years). Daughters of mothers of <or=20 years, on the other hand, did not appear to have reduced fecundity.


CONCLUSIONS
The results point to a decreased fecundity of daughters of older mothers, but not of daughters of younger mothers. The inconsistency of the results with respect to the oocytal-maturation hypothesis points to the action of other causal or non-causal mechanisms.
Smits
Luc J
LJ
Department of Epidemiology and Biostatistics, University Medical Center, Nijmegen, The Netherlands. luc.smits@epid.unimaas.nl
Zielhuis
Gerhard A
GA
Jongbloet
Piet H
PH
Van Poppel
Frans W A
FW
D000293:Adolescent; D000328:Adult; D005190:Family; D005260:Female; D005298:Fertility; D006801:Humans; D008423:Maternal Age; D015999:Multivariate Analysis; D009426:Netherlands; D010053:Ovary / Q000502:physiology; D011247:Pregnancy; D011256:Pregnancy Outcome