Maternal Age and Contractility of Human Myometrium in Pregnancy.

There is controversy as to whether maternal age exerts an influence on the contractility of human myometrium in pregnancy. The aim of this study was to examine a series of functional contractile parameters of human myometrium in vitro, over a broad range of maternal ages. Myometrial tissue specimens were obtained at cesarean delivery from 32 women with maternal ages ranging from 28 to 52 years. Using in vitro recordings, a number of contractile parameters including maximal amplitude, mean contractile force, time to maximal amplitude, maximum rate of rise, and occurrence of simple and complex (biphasic and multiphasic) contractions were examined for spontaneous and induced contractile activity. The relationship between maternal age and individual parameters was evaluated using linear regression analysis. For all contractile parameters examined, for both spontaneous and induced contractions, no significant correlation was observed with maternal age between 28 and 52 years. The mean maximum amplitude values for spontaneous and oxytocin-induced contractions were 23 ± 3 and 43 ± 5 mN, respectively. The mean contractile forces for spontaneous and oxytocin-induced contractions were 1.5 ± 0.2 and 6.5 ± 0.9 mN, respectively. There was no variation in the proportion of biphasic or multiphasic contractions with maternal age. These results indicate there is no significant functional impairment of uterine contractility and no lack in responsiveness of myometrium in vitro, in the older mother. These findings do not support the concept that there may be a biological basis for dysfunctional labor or increased cesarean delivery rates in older parturients.