This paper reports on the status of lactose digestion during early and late pregnancy and at 8 weeks postpartum in an African-American population. The hypothesis is that lactose digestion and milk tolerance do not change throughout pregnancy anddo not differ from those of non-pregnant African-American women.

This longitudinal study determined lactose digestion after ingesting 240 ml of 1% fat milk containing 12g of lactose at: (1) early pregnancy, prior to 16 weeks (n = 148); (2) late pregnancy, 30–35 weeks (n = 77); and (3) 8 weeks postpartum (n = 93). One hundred and one comparably matched non-pregnant African-American women served as controls.

Prevalence of lactose digestion, as measured by breath hydrogen, was 80.2% in the control women, 66.2% in early pregnancy, 68.8% in late pregnancy and 75.3% postpartum. The prevalence of women reporting symptoms was approximately 20% regardless of lactose absorption status. However, the control women reported significantly more symptoms than did the pregnant women.

This study indicates that there is no significant change in lactose digestion during pregnancy. The prevalence of lactose intolerance for the pregnant African-American women studied is similar to that for non-pregnant African-American women and similar to previous prevalence reports in adult African-Americans. There was no change in the tolerance of lactose noted during pregnancy in these women. There were, however, fewer symptoms reported by the lactose-maldigesting pregnant women.