Determinants of adverse birth outcome in the West Shewa Zone, Oromia, Regional State, Ethiopia: Unmatched case-control study

An adverse birth outcome (ABO), which includes preterm births (PTB) and low birth weight (LBW), are major drivers of morbidity and mortality in neonates and infants [1, 2, 3]. ABO is also an important contributor to serious, short- and longterm, physical and mental disabilities, including perinatal and infant death; chronic health problems later in life, such as hypertension, ischemic heart disease, metabolic syndrome, stroke, diabetes, malignancies, osteoarthritis, and dementia; learning difficulties; and hearing and visual impairments [4, 5, 6, 7]. Preterm is defined as a baby born alive before 37 weeks of pregnancy are completed [8]. Low birth weight is defined by the World Health Organization (WHO) as a weight of less than 2,500 grams for a live-born infant at birth [8].The majority of severe adverse outcomes during pregnancy and chldbirth result in the death of the mother or her offspring [9,10]. Globally in 2019, 2.4 million children died in the first month of life and about 6,700 neonatal deaths occurred every day; the first 28 days of life were the most vulnerable time for children under age 5 [11]. Regionally, the neonatal mortality rate is highest in Sub-Saharan Africa, followed by Central and Southern Asia. A child born in Sub-Saharan Africa is 10 times more likely to die in the first month of life than a child born in a high-income country and 12 times more likely to die than a child born in Australia or New Zealand [11]. ABOs are influenced by a different of biological, psychosocial, and environmental factors [12, 13, 14]. Different studies indicated that socioeconomic status, maternal education, marital status, pregnancy desire and teenage pregnancy, maternal comorbidities, and genetic vulnerabilities are also linked to poor pregnancy outcomes. Moreover, low pre-pregnancy body mass index (BMI), inadequate weight gain, and poor prenatal care utilization, female foetus, and self-reported cigarette smoking history are related to poor birth outcomes [15, 16, 17]. A high level of anxiety and depressive symptoms during childbirth and pregnancy have been related to a higher risk of adverse birth outcomes [10,14].

In Ethiopia, different studies have shown that the prevalence of ABOs is within the range of 13.9% to 37.6% [18, 19, 20, 21, 22, 23, 24]. Antenatal care (ANC) follow-up, rural residency, pregnancyinduced hypertension, advanced maternal age, current pregnancy complications, anaemia, and twin pregnancy were factors associated with ABOs [18, 19, 20, 21, 22, 23, 24, 25]. Though a few earlier studies were conducted in Ethiopia, those studies were cross-sectional and therefore weak in identifying those factors; those studies were also mainly conducted in single town or district [21,24,26, 27, 28]. Additionally, no other study has been conducted on determinants of ABOs in the study area. Therefore, the current study aimed at identifying determinants of adverse birth outcomes in the West Shewa zone, Oromia, regional state, Ethiopia, by using unmatched case-control study design.

This study tried to identify determinants of ABOs among mothers who delivered in hospitals in West Shewa zone. Women’s place of residence was found to be significantly associated with ABOs. Those women residing in urban areas were 1.5% less likely to develop ABOs than those in rural areas, a result similar to that found in studies reported elsewhere in Ethiopia (in Gamo Gofa zone, Hosana town, and northern Wollo) and in China [22, 23, 24, 25]. This could be due to the relative lack of access in rural areas to quality pregnancy-related care, including medical services, health information, and nutritional awareness.

The number of antenatal care (ANC) visits is significantly associated with ABOs: mothers who had fewer than four ANC visits were twice as likely to have ABOs as those who had four or more such visits. This finding is supported by studies conducted in Cameroon, India, Malawi, Addis Ababa, and in Ethiopia, in Tigrai region, Amhara region,and North Shewa zone [31, 32, 33, 34, 35, 36, 37]. This might be because mothers who have four or more ANC visits gain access to different or additional health promotion and preventive interventions that enhance the health of both the mother and foetus.

Having a history of current obstetric complications was also found to be significantly associated with ABOs. The chance of developing an abnormal birth outcome among mothers with current histories of child-related abnormal birth outcome was twice as high as the chances of mothers without such complications. A study conducted in Gambia and Nigeria showed that mothers with a current history of child-related abnormal birth outcomes are at greater risk of giving birth to a baby with abnormal outcomes [38,39]. Similar findings were previously reported in Ethiopia [21,23,24]. The link may be explained by the impact on the well-being of the foetus in the uterus of complications affecting the mother during pregnancy [40].

Mothers who have no support during childbearing had a five times greater chance of developing adverse birth outcomes as compared to mothers who have partner support. This study was in line with a study done in the United States that found that women with a supportive partner were 63% less likely to have low birth weight infants and nearly two times less likely to have a pregnancy loss, as compared to those with no partner support [30]. Those who have paternal support may experience less stress and thus be more likely to enter prenatal care; they may also be more likely to report a desired pregnancy, which may also reduce their risk of poor birth outcomes.

Short inter-pregnancy interval is also found to be a determinant of ABOs. The odds of having an ABO were 1.43 times greater among mothers with short birth intervals, as compared to mothers having optimal birth spacing. This result is in line with studies in Tanzania; California, Ohio, and elsewhere across the United States; and Bangladesh [41, 42, 43, 44], which showed short inter-pregnancy intervals were a risk factor for low birth weight and/or preterm birth. For example, a study conducted in Tanzania found that women who conceived at either shorter (less <24 months) or longer (37 to 59 months or more) inter-pregnancy intervals had a greater risk of preterm birth [41], and studies conducted in California, Ohio, and elsewhere across the United States showed that intervals shorter than 6 months might be associated with increased risk of adverse outcomes in the subsequent pregnancy [42,43]. Study results from Bangladesh showed that a very short birth interval less than 21 months (birth-to-pregnancy of less than 12 months when pregnancy is carried to term) is associated with an increased risk of adverse pregnancy outcomes, but intervals of 24 to 32 months (birth-to-pregnancy interval of 12 to 23 months when pregnancy is carried to term) and 33 to 44 months (birth-to-pregnancy interval of 24 to 35 months) do not appear to be [44]. This could be because short inter-pregnancy interval results in maternal nutrition reduction, which compromises the mother’s ability to support foetal growth and development, which in turn increases the risks of preterm birth, growth restriction, and maternal morbidity and mortality in the subsequent pregnancy [40,45].

In this study, mothers having current obstetric complications were three times more likely to develop adverse birth outcomes as compared to mothers with no history of current complications. This result is supported by studies conducted in Gondar, Ethiopia; Hosanna, Ethiopia; and a university and hospital in Nashik, India. [19,23,32].

The result of this study revealed that residence, lack of family support during childbearing, pregnancy type, short inter-pregnancy interval, current obstetric complications, and a number of ANC visits were determinants of adverse birth outcome. Therefore, improving family support, inter-pregnancy intervals through family planning counselling and provision, having the recommended ANC visits, were recommended.