Anemia in pregnancy: case control study of risk factors D.O. Selo-Ojeme* of Obstetrics
and Gynaecology, 20 May
Trust, Essex, United Kingdom
1 July 1997; accepted
2 July 1997
Anemia; Pregnancy; Risk factors
The high maternal mortality rates in most of the developing world are mostly attributable to preventable causes [l]. The identification of women at risk of some of these complications would enable them to benefit from improved surveillance and early medical intervention. Anemia is one of such complication and it causes maternal death both directly and indirectly. It is also associated with significant maternal morbidity and poor perinatal outcome . Although some factors which predispose pregnant women to anemia have been identified , there is no consensus on their significance or relative importance [3,4]. This prompted this prospective case control study at the Obafemi Awolowo University Teaching Hospital, Ile-Ife, Nigeria. The cases were 275 pregnant women at their first clinic visit who were anemic [packed cell volume (PCV> of less than 33%1 and the
0 1997 International
controls were another 275 without anemia (PCV 33% and above) seen after the indexed case but at the same gestational age. Information obtained from both groups included medical, obstetric and gynecological histories as well as sociodemographic characteristics of the patients and their husbands. Their peripheral blood smears were examined for parasitemia. Excluded from the study were recently transfused pregnant women, patients with hemoglobinopathies, early pregnancy bleeding or anteparturn hemorrhage and those on hematinics. Gathered data were fed into the computer and the strength of association of the hypothesized risk factors in both cases and controls were quantified. The odd ratios and confidence intervals were calculated and multiple logistic regression conducted using the SPSS PC + software. After adjustment for other factors, primigravid women were five times at increased risk of developing anemia. In women with interpregnancy interval of two years and less and in those with twin and Obstetrics
pregnancies or malaria parasitemia, the risk was increased fourfold. It was increased threefold when the patient was in the low socioeconomic group (Table 1). The increased risk of anemia in the primigravidae was confirmed in this study. No association with grandmultiparity was found. The influence of malaria parasitemia was not surprising as resistance to malaria is diminished during pregnancy leading to increased frequency and density of parasitemia with resultant hemolytic anemia. When birth intervals are short, adequate replenishment of iron stores is prevented increasing the predisposition to anemia. This underscores the need for birth spacing programs. Nutritional deTable 1 Odds ratios (OR) and 95% confidence interval (CD of characteristics associated with pregnancy anemia: multivariate analysis Characteristics
Crude OR (95% CI)
Adjusted OR’ (95% CI)
Para 0 Pregnancy interval < 2 years Twin pregnancy Malaria parasitemia Low social class Polygamous marriageb
3.7 (2.5-5.4) 7.0 (3.9-12.4) 3.6 (1.3-10.4) 7.0 (4.5-10.7) 2.43 (1.7-3.4) 1.78 (1.1-13.8)
5.64 (3.7-8.2)* 4.88 (2.7-8.75)** 4.8 (1.6610.4)** 4.1(2.7-6.2)* 3.25 (1.9-5.8)*** 1.8 (0.2-6.41
’ Adjusted for age, parity and malaria parasitemia. b 128 cases and 208 controls. * P < 0.001, **
P < 0.01, ** P < 0.03.
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mands are increased by multiple pregnancy and maybe unmet by low socioeconomic class. Pregnant women with these factors should be screened for anemia and appropriate action taken to forestall complications.
I acknowledge the assistance of Professor Friday Okonofua in the conduct of this study.
[ll Adetore 00. Maternal mortality. A 12 year review at the University of Ilorin, Nigeria. Int J Gynecol Obstet 1987;25:93-99. World Health Organisation. Prevention and manage121 ment of severe anaemia in women: a tabulation of available information. Maternal health and safe motherhood program. Nutrition program. 2nd edition, WHO/MCH/MSM/92.2. Geneva: WHO, 1992. [31 Desalgn S. Prevalence of anaemia in Jima town, Southwestern Ethiopia. Ethiop Med J 1993;31:251-258. [41 Mahfouz AA, El-said MM, Alakija W, Badawi IA, alErian RA, Moneim MA. Anaemia among pregnant women in the Asir region, Saudi Arabia: an epidemiological study. Southeast Asian J Trop Med Public Health 1994;25:84-87.