Mice give birth to bouncing babies if they have their first litter as young adults, a Brief Communication reports this week in Nature (VOL. 407 NO. 6803 DATED 28 SEPTEMBER 2000, pp. 469-470). Male pups born to early adolescent and middle-aged mothers tend to be smaller, and have delayed puberty and smaller reproductive organs, Frederick vom Saal and Ming-Hseng Wang at the University of Missouri, Columbia, report.
Different hormone levels during pregnancy are the culprit. The youngest and oldest mice have less serum oestradiol and a different pattern of serum testosterone when pregnant than do young adult animals.
In turn, female offspring also produce pups whose birthweight depends on their maternal grandmother’s age when first pregnant. Because very early and very late pregnancies are becoming increasingly common in people, the researchers say that the influence of age-related changes on offspring merits further investigation.
Frederick vom Saal
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