BACKGROUND:Less than optimal reproductive conditions may be associated with a secondary sex ratio biased towards females. Body weight represents a critical determinant of reproduction. Accordingly, we evaluated whether preconception body weight and weight gain during pregnancy influence the sex ratio of human offspring.METHODS:A retrospective study was performed on 10 239 births in 1997-2001. Time of conception, preconception body weight and net weight gain during pregnancy were obtained for 9284 pregnancies.RESULTS:The secondary sex ratio of mothers in the lowest quartile of pre-pregnancy body weight (<54.6 kg) was lower than that of the other three quartiles (0.497 versus 0.525; P < 0.01). In contrast, the sex ratio of children born by the women in the highest quartile of weight gain during pregnancy appeared lower than that of the first three quartiles (0.493 versus 0.516; P = 0.054).CONCLUSIONS:A low pre-pregnancy weight and a greater weight gain during pregnancy are both associated with a reduced secondary sex ratio. These data indicate that in women with non-optimal reproductive/metabolic conditions, a greater attrition is exerted on male than on female offspring.

Influences of maternal weight on the secondary sex ratio of human offspring

CAGNACCI, Angelo
;
2004-01-01

Abstract

BACKGROUND:Less than optimal reproductive conditions may be associated with a secondary sex ratio biased towards females. Body weight represents a critical determinant of reproduction. Accordingly, we evaluated whether preconception body weight and weight gain during pregnancy influence the sex ratio of human offspring.METHODS:A retrospective study was performed on 10 239 births in 1997-2001. Time of conception, preconception body weight and net weight gain during pregnancy were obtained for 9284 pregnancies.RESULTS:The secondary sex ratio of mothers in the lowest quartile of pre-pregnancy body weight (<54.6 kg) was lower than that of the other three quartiles (0.497 versus 0.525; P < 0.01). In contrast, the sex ratio of children born by the women in the highest quartile of weight gain during pregnancy appeared lower than that of the first three quartiles (0.493 versus 0.516; P = 0.054).CONCLUSIONS:A low pre-pregnancy weight and a greater weight gain during pregnancy are both associated with a reduced secondary sex ratio. These data indicate that in women with non-optimal reproductive/metabolic conditions, a greater attrition is exerted on male than on female offspring.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11390/1105785
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