Anemia in pregnancy in the highlands of Tanzania.

BACKGROUND: Anemia in pregnancy is common in Tanzania, but many areas have not been investigated. This study describes prevalence and determinants of anemia among rural pregnant women living at 1300-2200 meters above sea level in Northern Tanzania.
METHODS: Three thousand eight hundred and thirty-six pregnant women from two rural divisions of Mbulu and Hanang districts attending antenatal clinic between January 1995 and March 1996 were assessed in a cross-sectional study. Blood samples were examined for hemoglobin concentration (Hb) and thick blood slide (BS) for malaria. Information on date of examination, village, age, ethnic and religious affiliation, gestational age, and parity was recorded. Altitude was derived from official maps. Main outcome measures were mean Hb level and risk of anemia defined as a Hb of less than 9.0 g/dl.
RESULTS: Hb levels ranged from 4.5 to 18.1 g/dl, and mean was 12.1 g/dl. Twenty-three per cent had a Hb of less than 11 g/dl, 4.6% less than 9 g/dl and 0.5% less than 7 g/dl; standardized to sea level 36.1%, 8.8%, and 1.1%, respectively. The mean Hb increased by 0.3 g/dl per 200 m increased altitude, and the risk of anemia decreased with a factor of 0.6 per 200 m increased altitude. We found higher risk of anemia at higher maternal age (1.2 times increased risk per 5 years). Furthermore, the Datoga tribe had twice the risk of anemia compared with the Iraqw. The risk of anemia was only half at 3-4 months of gestation compared to at 7-8 months. The risk increased six-fold in the rainy season of 1995, and the risk was almost double among those with malaria parasitemia.
CONCLUSIONS: Anemia in pregnancy was common in this area of high altitude in rural Tanzania, but less prevalent than indicated by studies from most other parts of the country. The study confirms that preventing anemia is a challenge in preventive antenatal care in the highlands of Tanzania. Studies focussing on the specific etiologic agents are needed.