Pregnancy, delivery and the newborn infant of 212 old primiparas (aged greater than or equal to 35 years) and of 1968 age-matched old multiparas as controls were studied for the 1970-1989 period. The frequency of old primiparas and old multiparas was 0.9% and 4.1%, respectively, with no change for the 1970-1979 (1.0%) and 1980-1989 (0.8%) periods. The mean age in the old primiparous and old multiparous groups was 38.08 + 4.2 and 38.2 + 4.8 years, respectively (P greater than 0.05). The old primiparas had an average of 7.37 +/- 2.8 antenatal visits, whereas the old multiparas had 6.08 +/- 3.3 visits (P less than 0.05). The old primiparous group included more employees and fewer unskilled workers and housewives (P less than 0.05), more urban and unmarried pregnant women (P less than 0.001), whereas the old multiparas had more spontaneous and induced abortions (P less than 0.05). Threatened abortion (23.7%), EPH gestosis (20.3%), meconium-stained amniotic fluid (21.7%), caesarean section (35.8%), placental lysis or uterine exploration (6.6%) and episiotomy (100.0%) are more frequent in old primiparas than in old multiparas (P less than 0.05). The duration of labour in old primiparas tends to be longer: there was a significantly smaller number of pregnant women with an up 6-hour duration of labour (42.5%; P less than 0.05). The average duration of labour in the old primiparous and old multiparous groups was 8.18 +/- 5.40 and 5.89 +/- 3.80 hours, respectively (P less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)