Post-partum anemia is a common problem throughout the world and the prevalence is high in developing countries where it ranges between 50% and 80% [1]. Post-partum period begins immediately after the delivery of the placenta and lasts up to 42 days. It is the most critical period for the health and survival of both the mother and her neonate [1]. Post-partum anemia (haemoglobin level of less than 11g/dl) is one of the commonest puerperal complications and major cause of maternal morbidity and mortality [2]. In developing countries, the most important causes of post-partum anemia are prepartum iron deficiency and/or iron deficiency anemia combined with acute bleeding anemia at delivery, infections such as malaria, intestinal worms; disease conditions such hemoglobinopathies, poor socio-economical conditions and nutritional deficiencies [1–4]. Other related factors include education level, income, age, parity, birth spacing, antenatal care, blood loss and delivery complications [5]. Post-partum haemorrhage and pre-partum anemia may also cause postpartum anemia in 5% to 25% [5]. While anemia has been studied extensively in pregnant women, the extent and impact of anemia during the postpartum period has more recently become an area of interest [6].

The prevalence of anemia in Tanzanian women during pregnancy and after delivery is unacceptably high. A cross-sectional study conducted in a capital city, Dodoma in 2020 found the prevalence of postpartum anemia to be 21.6% [7]. A study on determinants of anemia in postpartum HIV-negative women in Dar es Salaam found that at baseline, 67.4% of the population was anemic [4]. Maternal nutritional status during pregnancy, prenatal iron/folate supplementation, perinatal care, and prevention and management of infections, such as malaria, were modifiable risk factors for the occurrence of, and recovery from, anemia [4, 7, 8].

Anemia during pregnancy is associated with adverse maternal health, possibly contributing to maternal mortality, and with poor pregnancy outcomes, including low birth weight, premature birth, neonatal and infant morbidity, and mortality, as well as reduced newborn iron stores and subsequent cognitive impairments [7]. The mother’s health status during pregnancy and postpartum period affects the potential for breastfeeding, and consequently the risks of anemia in infancy [1]. This is more apparent in mothers below the poverty level, including those from developing countries.

Severe pre-partum anemia has a negative impact to both maternal and child health, as it is associated with increased risk post-partum haemorrhage, depression, reduced cognitive functions and urinary tract infection, fatigue and exhaustion, insufficient milk syndrome and reduced breast milk quality [7–10]. Severe anemia may also leads to delayed wound healing, reduced immunity, increased susceptibility to breast infection like mastitis, ductitis, and hence has major impact on maternal and child’s health [11]. Previous studies have also shown that recovery from anemia after delivery was slower for low-income women relative to those with family income above the poverty line [6, 12].

Studies on the burden of post-partum anemia and associated risk factors among women in Tanzania are limited. Understanding the risk factors associated with post-partum anemia may help provide valuable information that can be useful in the intervention strategies to reduce anemia and its complications. This study aimed at determining prevalence and factors associated with post-partum anemia among women attending public primary health care facilities in Dar es Salaam, Tanzania.

A total of 447 post-partum women were assessed for eligibility into this study and 23 did not meet the criteria thus, were excluded. The reasons for exclusion were; currently taking iron supplements and or anti-parasitic medication for malaria and or helminthiasis (n = 9), history of malignancy/pre-malignancy (n = 7), hemoglobinopathies (n = 4), and not willing to participate into the study (n = 3). Thus, a total of 424 postpartum women were recruited in this study. Each facility contributed about a third of the participants. Their mean age was 27 years (SD 5.93). Majority 338 (79.7%) of the participants aged between 20 and 34 years; 234(55.2%) had primary education and nearly half 198(46.7%) of them were house wives. Of 424 enrolled women, 145 (34.2%) had anemia (HB level of less than 11g/dl). The parity and marital status showed statistical significant association with post-partum anemia (p<0.001), Table 1. Majority 179(42.2%) of the study participants were having three or more parities. Most women 340(80.2%) booked antenatal care at the second trimester and 244(57.6%) had three to four visits, Table 2. Among obstetric factors evaluated, pregnancy interval between the last two pregnancies and mode of delivery in the last pregnancy were significantly associated with post-partum anemia (p<0.05), Table 2.

Table 3 summarizes utilization of key interventions for preventing anemia during antenatal and postpartum period. Majority of the participants 406(95.8%) received iron and folic acid (IFA) tablets while 378(89.2%) were dewormed during pregnancy. Most of the participants received between two 113(26.7%) and three 131(30.9%) doses of malaria prophylaxis (SP); and majority of them 418(98.6%) did not use insecticide treated nets (ITNs). Among antenatal interventions provided for prevention of anemia, among participants who utilized ITNs, none of them had anemia. At the same time the association between other preventive measures and risk of post-partum anemia did not attain any significant association, Table 3.

Nearly one quarter (23.5%) of participants with postpartum anemia had positive blood slide for Malaria falciparum parasites, while 15(10.3%) of them had helminthiasis, Table 4. Post-partum women with less than two years interval between the last two pregnancies were about 18 times likely to have anemia than women with more than two years interval, (COR = 18; 95% CI 8.617–38.617), Table 5. Single women were 10 times more likely to get anemia compared to married women. (COR = 10; 01.910–54.935). The risk of post-partum anemia was decreased (COR = 0.2; 95% CI 0.084–0.418) in women who delivered per vaginally as compared to those delivered by cesarean section. The risk of anemia was decreased in women with low parity compared to those with high parity (COR = 0.3; 95% CI 0.147–0.652), Table 5.

Prevalence of post-partum anemia in our study was 34.2%. This study highlighted that post-partum anemia is a significant public health problem in Tanzania. It has also recognized several factors associated with post-partum anemia such as delivery by cesarean section, child spacing, absence of a marital partner and increased parity of which have policy implications.

In the current study the prevalence of anemia during post-partum period was much lower compared to a study done in Uganda which reported the prevalence of anemia in nearly two thirds of the participants [15]. Such a big difference may be due to variation in hemoglobin cut- off points used to define post-partum anemia. However, the prevalence of anemia in this study is higher compared to the studies done from high income countries [16]. Advancements in health facilities and maternal living conditions in the western countries as compared to Tanzania could explain the observed differences. However, the high prevalence of post-partum anemia observed in our study highlights a need for further improvement in maternal nutrition and the general health of the women before and during pregnancy as well as post-partum period. Over the years, Tanzanian government through the Ministry of Health has been trying to strengthen antenatal care (ANC) services across the country. Currently, every pregnant woman has free access to iron supplementation to combat anaemia, deworming agents, malaria prophylaxis, and mosquito nets [17, 18].

In the current study, delivery by vaginal route was protective against post-partum anemia and the risk of post-partum anemia decreased in women who delivered per vaginally as compared to those delivered by cesarean section. The exact reason for this observation is obscure. Perhaps high risk of post-partum hemorrhage and hemorrhage related morbidity in cesarean delivery group may have resulted into higher prevalence of post-partum anemia compared to vaginal delivery, [19, 20]. This finding reminds the health care providers to take preventive measures against complications of post-partum anemia. Such prevention measures include screening, prophylaxis with iron tablets and treatment.

The inter pregnancy interval was significantly associated with post-partum anemia in the current study. The risk of post-partum anemia was found to be 10 times when the interval is less than two years between the last two pregnancies as compared with those with more intervals. This finding is consistent with previous reports [21, 22]. This is likely due to the fact that mothers may not yet replenished essential nutrients especially iron and folic acid which were depleted by the previous pregnancy. In this study, maternal age was not found to be significantly associated with post-partum anemia. Other investigators have also found no correlation between anemia in post-partum period and maternal age [19, 20]. However, younger maternal age has been implicated in the development of post-partum anemia because this age group tends to have incomplete growth, lesser utilization of prenatal and postnatal services and psychological factors [23].

Low parity was found to be protective against post-partum anemia in our study. Parity or number of previous pregnancies has been shown to impact the long term health status of women specifically anemia. The women with more than two pregnancies had significantly higher rate of anemia. Increasing parity has also been established to be associated with post-partum anemia by previous investigators [1–5]. This might be due to increase of women’s nutritional demand during pregnancy. Women with prior pregnancy sustain between 500mg and 600mg of iron loss per pregnancy which includes addition to daily iron loss in that part of gestation. Iron requirement directed towards the fetus and the placenta (300mg to 350mg) and puerperal blood loss (200mg to 250mg). Blood loss during delivery will also increase this loss. Anemia is therefore much more common as parity increase.

Our study has highlighted that women with no formal marital partners were more likely to get anemia as compared to married women. A study done in Ghana found no association between marital status and post-partum anemia [5]. The reason for the association found in the present study is not clear. Perhaps it was by chance. However, lack of consistent and reliable moral and socio-economical support from the male partner who is essential for health pregnancy may explain this observation. Women without permanent marital partners are likely to be financially unstable especially during pregnancy when their ability to engage in income generating activities is compromised and thus vulnerable to poor living conditions leading to poor nutrition in this group as compared to the married women [24, 25].

In the current study it was observed that 89.2% and 96.1% of the total study participants consumed hematinics and iron supplements respectively during pregnancy. There was a reason to believe that women’s lack of nutritional inputs predates post-partum anemia. It has been seen that despite of iron and folic acid and anti-hematinics consumption, post-partum anemia is still prevalent in this population. Perhaps women had high levels of nutritional deficiency prior pregnancy so that the supplemental iron was not enough to correct anemia. On the other hand women reporting consumption of hematinics might not be consuming them in reality and this needs further researching [26].

Although our study did not find any statistical significant association between booking time for ANC and post-partum anemia, other researchers have clearly established a positive correlation between late ANC booking and postpartum anemia. Early ANC plays a major role in preventing anemia [7, 23]. This is due to failure to benefit from chemoprophylaxis and late diagnosis and treatment of anemia among women who delay in utilizing ANC services. Therefore, in line with ANC guidelines by the World Health Organization as well as the Ministry of Health, Community Development, Gender, Elderly and Children; programs aiming at early ANC booking are highly emphasized. Women should attend ANC as soon as they find out that they are pregnant [17, 18].

The prevalence of malaria and helminthes parasite infections among participants in the current study is considerably high, despite the reported high utilization of preventive treatment during pregnancy. Our results agree well with previous study [27] in Tanzania which reported a significant correlation between anemia with malaria. A study from Kenya reported the prevalence of geohelminths, malaria parasites, and co-infections of 24.7%, 21.6%, and 6.8%, respectively [28]. The findings may suggest that the burden of malaria and helminths co-infections is still a problem in sub-Saharan Africa. HIV infection was not found to be significantly associated with post-partum anemia in our study. This may be explained by early access to anti-retral viral therapy (ART) immediately after diagnosis so as to enable prevention of mother to child transmission [29]. ART given to those women helps in boasting their immunity and down regulate the impact of HIV.

Our study has a number of limitations. First, it was conducted in primary public health care facilities, hence targeted only women who visit health units, missing out those with limited resources for transport, those who may have lost their children at birth and thereafter and those with poor health seeking behaviors. Second, the study missed out women who had died under circumstances where anemia played a role. Third, other factors like cultural and dietary habits were not included in the study and thus a larger, community-based study is recommended as most of Tanzanian women give birth in their home places. Fourth, the nature of study design, being a cross section study, does not show which preceded the other between post-partum anemia and risk factors. Moreover, were unable to determine the last hemoglobin levels of the participants before they gave birth, thus missing the possible major causes of postpartum anemia which include pre-partum anemia. Similarly, convenient sampling instead of random sampling technique was used to obtain study participants. Hence, interpretation of the study findings needs to be done cautiously. Lastly but not least, hemoglobin determination by the kit used in this study may not necessarily reflect the actual current situation.

The prevalence of post-partum anemia in public primary health care facilities in Dar es Salaam was 34.2%. Absence of a marital partner and less than two years interval between the last two pregnancies were significantly associated with anemia in post-partum period while low parity and delivery by vaginal route were protective. The high prevalence of post-partum anemia found in this study highlights the importance of screening and treating prepartum anemia as well as provision of education on ideal child spacing which may constitute an important approach for reducing the prevalence of anemia.