Summary. Sixty-nine primigravidae, 59 of them aged between 13 and 16 years, were placed on various combinations of antimalarial drugs, folic acid and iron throughout the second half of pregnancy and the puerperium. Between their first attendance at the antenatal clinic and 1–60 days after delivery, more than half of these pregnant teenage girls increased in height by 2–16 cm. Haematinic supplementation and growth of both the fetus and the mother were found to be linked. When compared with girls who did not receive nutritional supplements, a significantly greater proportion of girls who were supplemented grew by ≥2 cm during pregnancy and showed a significant correlation between increase in height and mean weekly weight gain. This growth during pregnancy was highly related to the haematocrit level at the 28th week of pregnancy, after an average of 10 weeks' treatment. Fetal birthweight was correlated with serum folate activity at the 36th week of pregnancy. Because young teenage girls continue to grow during pregnancy, when determining the relation between their heights and reproductive performance, calculations must be based on heights taken towards the end rather than at the beginning of pregnancy.