At both extremes of reproductive phase female pregnancy outcome is described as poor. Beside a high rate of anovulatory cycles, pregnancies at these phases of the reproductive span are considered as risky for obstetric complications, and increased maternal and newborn morbidity and mortality. In the present study the associations between the age as well as somatic characteristics such as prepregnancy weight, stature, pelvic dimensions and pregnancy weight gain of 10765 women ageing between 12 and 49 years and newborn body dimensions and the mode of delivery as well as uterine child presentation were analysed. With increasing maternal age, maternal and newborn body dimensions increased significantly. Furthermore, extremely young mothers showed the lowest rates of caesarean sections, while mothers older than 40 years experienced the significantly highest rate of caesarean sections. Regarding newborn weight status, for mothers older than 35 years the highest rate of low weight newborns (< 2500 g) and the highest rate of macrosome newborns (> 4000 g) were found. Special risks were found in mothers older than 35 years, so the lower rates of ovulatory cycles during this phase of life may be interpreted as an adaptation to increased risks for complications and poor pregnancy outcome.