Preterm Delivery and Associated Factors Among Women Who Delivered Live Babies at Muhimbili National Hospital, Dares Salaam, Eastern Tanzania.

Introduction

Preterm delivery is defined by the World Health Organization as all deliveries occurring before 37 completed weeks of pregnancy, or within 259 days after a woman's last menstrual period. Preterm delivery is further sub classified into mild preterm (34-36weeks), moderate preterm (32-33weeks), and severe preterm (28-31weeks) [1- 4]. Preterm newborns' outcomes and prognosis are now linked to their gestational age and birth weight at birth. Preterm delivery occurring between 28 and 31 weeks of pregnancy is considered as severe or very preterm, accounting for 1% of all preterm births [5].

After the WHO released global rates of preterm delivery, it became a global and public health priority [6]. Around 15 million babies are born preterm each year, accounting for 11.1% of all live births worldwide, ranging from 5% in various European nations to 18% in some African countries. More than 60% of preterm newborns are born in South Asia and Sub-Saharan Africa, which account for 52% of all live births worldwide [7]. Preterm delivery complications are the top cause of mortality in children under the age of five worldwide, accounting for around 16% of all fatalities and 35% of deaths among newborn newborns.

According to reports from a number of high-income and high- middle-income nations, preterm birth rates are on the rise worldwide, ranging from 5 to 7% in affluent countries and substantially higher in underdeveloped countries. Surviving preterm newborns are more likely to experience a range of short and long-term morbidities. Respiratory distress syndrome, bronchopulmonary dysplasia, necrotizing enterocolitis, sepsis, periventricular leukomalacia, seizures, intraventricular hemorrhage, cerebral palsy, infections, feeding difficulties, hypoxic ischemic encephalopathy, and visual and hearing impairment are all common complications experienced by preterm newborns. Preterm delivery is also attributed to large resource expenses for health systems, and families with preterm babies frequently face major psychological, emotional, and financial consequences [8].

Tanzania like other sub-Saharan countries, is reported as among the top ten countries with the highest number of preterm deliveries worldwide with an estimated number of over 300,000 per year with an estimated prevalence of 16.6% [9].Preterm delivery is therefore a critical global health issue that continues to be a great concern for obstetric and pediatric units, particularly in Sub-Saharan Africa, and must be addressed in order to minimize newborn and child mortality and achieve the Sustainable Development Goals [10- 12]. In Sub-Saharan countries, the attention given to preterm delivery is less and significant effort are emphasized in the care of premature infants but not in reducing the proportion of preterm delivery which is generally on the rise [13].

Regardless of the burden, Tanzania like other developing countries, has limited studies locally and therefore, little is known about the burden and factors contributing to preterm delivery in the country. Therefore, the current study was intended to determine the magnitude of preterm delivery and the associated factors at Muhimbili National Hospital, tertiary hospital in Tanzania.

Materials and Methodology

Study Design

A hospital-based cross-sectional study was conducted at Muhimbili National Hospital's maternity unit (MNH).

Study Duration

The study was conducted from 9th August to 30th October, 2021.

Study Setting

The study was conducted at MNH, the largest tertiary National referral hospital in Tanzania, which serves as a teaching hospital and research facility for Muhimbili University of Health and Allied Science (MUHAS) and Other Medical Training Colleges. It offers specialized obstetric services and care for Dares Salaam, capital city and suburban population of about 4364541millions people [14]. The hospital comprises a maternity unit block with four wards for neonatal and postnatal care, each of which houses 40 women, a maternity high depending unity, an intensive care unit, and labor ward. It attends high risk pregnancies which end up in preterm delivery such as women with severe forms of hypertensive disorders in pregnancy.

Muhimbili National Hospital maternity unit receives women directly from home and those who are referred from almost all regional and district hospitals residing in Dares Salaam and other regions in Tanzania. The Labor wards can have four rooms which conduct between 16 to 20 deliveries per day, over 600 deliveries per month, and over 7000 deliveries annually. All women who delivered at MNH, their data were captured in an electronic health record system. MNH also has a special neonatal intensive care unit (NICU) which offers specialized neonatal care to premature newborns and sick babies delivered at MNH and those referred from other facilities for specialized care.

Study Population

The study population comprised of all women who had live births at Muhimbili National Hospital (MNH) during the study period.

Sample Size

The sample size was determined by using the modified Kish and Leslie single proportion formula by considering the 95% confidence interval and 0.04 degree of accuracy, and the proportion of preterm birth from Chawanpaiboon et al., 2019, which was 16.6% as the overall prevalence of preterm delivery in Tanzania. By adding a 10% non-response rate, the final minimum required sample size was 422 women included in the study.

Inclusion Criteria

All mothers who had a live birth at MNH at GA of 28, completed weeks and above, and consented to participate were enrolled in the study.

Exclusion Criteria

All mothers who had a live births at MNH who were too sick and unable to consent.

Sampling Procedure

Systematic random sampling strategy was used to select study participants who met the inclusion criteria, During the study period MNH labor ward was conducting an average of 16 deliveries daily of live births, which is equivalent to around 480 deliveries per month. The sampling interval was calculated by dividing the 480 women who had a live baby in a month by the minimum adjusted sample size. The first participant to be included in the study was chosen randomly through a lottery by blindly picking one of the five pieces of paper named for the first five mothers in each day and then every second woman who gave birth after that was added to the study until the target sample size was reached. Gestational age of the newborn was calculated based on mother LMP or early ultrasound results. Ballard score, which was available in the neonatal unit, was used for calculation of age of the baby when the mother did not remember her last day of the last normal menstrual period and early ultrasound information was not available [15].

Data Collection Tools and Techniques

This study used primary data which was collected from maternity wards, from Monday to Sunday, all postnatal mothers who had a live birth within 24 hours of delivery were identified from the delivery registry book in the labor ward which was the entry point during our study and then followed to their respective wards. Data was collected by using a face-to-face interviewer administered questionnaire. The language used in the questionnaires was Swahili, which is a local language and widely spoken by all Tanzanians. The questionnaire collected data on socio-demographic factors, previous pregnancy characteristics, antenatal characteristics, pregnancy complications (obstetrical factors), and maternal medical conditions among women who delivered a live baby at MNH. In addition, the clinical case record and the delivery book were studied to extract medical information that could not be obtained through an interview. Maternal background information, obstetrics history information, and history of previous preterm birth were all collected from the mother. Preterm prelabor rupture of membranes, pregnancy- related hypertension, antepartum hemorrhage, gestation diabetic mellitus, and history of burning sensation during pregnancy or treatment for urinary tract infections were among the details extracted from the patient medical records. Anemia was defined as a hemoglobin level of <11 g/dl as documented by the attending clinicians and midwives during admission or antenatal follow-up. Pregnancy related hypertension was defined as documented by the attending clinician as a blood pressure of > 140/90 mmHg after 20 weeks of pregnancy with or without proteinuria. Gestational diabetic mellitus was defined as increased blood sugar after 24 weeks of gestation as documented by the attending clinician. Any vaginal bleeding in the mother after 28 weeks of pregnancy was characterized as antepartum haemorrhage as documented in the records by the attending clinician, urinary tract infection was defined as a documented clinical/laboratory diagnosis at any time during the pregnancy and/or a positive history of UTI treatment as reported by the mother and documented by the attending clinicians.

Data Analysis

The information collected was organized, filtered, and double- checked for accuracy. Then were coded and entered into the computer and then were analyzed using SPSS software (Version 23; Chicago, IL, USA). Analysis was done by both descriptive and analytical statistics. Mean frequency and percentages were used in descriptive statistics. The chi-square (â?¹2) test and fisher exact test of association were used to establish associations between preterm delivery and the various associated factors. Bivariable and multivariable logistic regression model analyses were carried out to establish the strength of associated between the independent factors and preterm delivery. In bivariate logistic regression analysis, variables with p-value less than or equal to 0.2 were entered to multivariate logistic regression analysis to find the strength of association. Finally, a statistically significant association of variables were claimed based on the Adjusted Odds Ratio (aOR) with its 95% CI and P-value <0.05.

Results

During the study period, 422 mothers were enrolled, interviewed, and analyzed. The results indicated that 84 (19.9%, 95% CI;16.8- 22.6) mothers had a preterm delivery with a CI (16.8-22.6), out of which 56(13.3%) had a late preterm delivery (34-36 weeks of gestation) and 28 (6.6%) had early (28-33 weeks of gestation) preterm delivery. Out of the total 422 mothers included in this study, the mean age of the study participants was 27.00 (+ 7) with an interquartile range of ± 7. 74.4% of the study participants were ranging between 20 and 34 years old, 87.4% were married, 49.8% were self-employed mothers. According to the respondents' maternal education status, 39.8% of the mothers had completed a college or university education. (Table 1).

                                 Table 1: Socio-Demographic Characteristics of the Study Participants (N=422)

Majority (71.1%) of mothers were para, 1 to 3. 72.7% of the mothers had a birth interval greater than or equal to 2 years. 97% of the mothers had singleton deliveries. 99.8% of mothers had at least one ANC visit, while 85.5 % of those who attended ANC follow-up had four or more visits. Concerning delivery mode, vaginal delivery accounted for 58.3% of all deliveries (Table 2).

                              Table 2: Clinical and Obstetric Characteristics of the Study Participants (N=422)

Key: b; n=359, c; n=347, Frequencys did not tally with total due to missing values of variables, UTI: urinary tract infection. PPROM: preterm prelabor rupture of membrane, HIV: Human Immunodefiency virus, ANC: Antenatal care, HB: Haemoglobin.

According to bivariate analysis, the proportion of preterm de- livery was significantly higher in women who had history of preterm delivery, history of short interpregnancy interval, with less than 4 ANC follow-up, and low level of hemoglobin level during pregnancy. Concerning the obstetrical complications and maternal medical condition, mothers with maternal hypertensive disorders, Antepartum hemorrhage, PPROM, Multiple pregnan- cy, and Urinary tract infection were statistically significant asso- ciated with preterm-delivery (Table 3).

                              Table 3: Obstetrical and Medical Maternal Factors Associated with Preterm Delivery (N=422)

Key: *; n=372, n=361, Frequencys does not tally with total due to missing values of variables, PIH: Pregnancy related hypertension,APH: antepartum hemorrhage, PPROM: preterm prelabor rupture of membrane, HIV: Human Immunodefiency virus.

According to the logistic regression model, mothers with his- tory of preterm delivery were five times more likely to have preterm delivery compared to the contrary (aOR=5.36, 95%CI 2.53-11.33), mothers who had a short Interpregnancy intervals of less than 24 months were 3-times more likely to give preterm delivery compared to those with interval greater than or equal to 24months (aOR=2.95, 95%CI 3.08-9.06),mothers with ANC follow up of less than 4 visits were three times more likely to have preterm delivery compared to those who had more than four visits (aOR=2.99,95%CI 2.79-14.37), mothers with pregnancy related hypertension (PIH) were 11-times more likely to have preterm delivery compared to those with no PIH (aOR=10.75,95%CI 5.75-18.33),mothers who experienced antepartum hemorrhage (APH) were 14fold more likely to give a preterm delivery com- pared to women with no APH (aOR=14.46,95% CI 4.92–24.27) ,mothers who experienced PROM during pregnancy were 5fold to have preterm delivery compared to those who had not en- countered PROM (aOR =5.95, 95% CI 1.94 – 14.12),mothers with multiple gestation were almost 10folds to give preterm de- livery compared to mothers with single tone pregnancy (aOR = 10.65; 95% Cl; 4.41-17.98). Concerning the maternal medical conditions, the risk of preterm delivery increased in the 3-fold in mothers with a positive history of maternal urinary tract infec- tion (UTI) compared to women with no history of UTI (aOR = 3.08; 95% Cl; 2.467, 12.412). (Table 4).

                      Table 4: Univariate and Multivariate Analysis of the Factors Associated with Preterm Delivery.

Key: cOR: crude Odds Ratio, aOR: adjusted Odds Ratio, CI: confidence interval, Re: Reference group, PIH: Pregnancy related hypertension, APH: antepartum hemorrhage, PPROM: preterm pre-labor rupture of membrane, GDM: gestation diabetic mellitus, Pregn: pregnancy, UTI: urinary tract infection

Discussion

Preterm delivery is one of the most concerning health problems and remains as a major problem for both obstetric and pediatric teams at Muhimbili National Hospital. This study found that the prevalence of preterm delivery at Muhimbili National Hospital was 19.9%. Previous preterm delivery, short interpregnancy interval, maternal ANC follow-up of <4 contacts, multiple gestation, pregnancy-related hypertensive disorders antepartum hemorrhage, prelabor rupture of membranes and maternal urinary tract infections were identified as independent factors relating to preterm delivery.

The study demonstrated a significant higher prevalence of preterm delivery. This finding is consistent with other studies reported in sub-Saharan countries which had similar outcomes [16, 17]. The high rate of preterm delivery in this study is also in consistent with World Health Organization (WHO) estimates in which the highest rate was 18% in sub Saharan Africa. The present study's preterm birth rate is substantially higher than that reported by Temu et al and Mahande et al in northern eastern Tanzania [18].The difference in preterm delivery rates can be explained by the different study approaches and study setting. The prevalence in this study is lower than the 25% reported in Ethiopia, these differences might be attributed to differences in the study regions, which could be influenced by differences in social economic position, health seeking behavior, and the enhancement of various health programs.

Most previous studies have shown that previous pregnancy history is the most important factor which contributes to the increased risk of recurrence of preterm delivery. This study found that the previous pregnancy history was associated with preterm delivery, women with a history of preterm delivery in the preceding pregnancy were significantly associated with preterm delivery. This finding was similar to the findings of other studies [19, 20].This may be explained by the presence of persistence unidentified factors in some women precipitating preterm delivery reference.

This study also found that mothers with a short interpregnancy pregnancy intervals of < 24 months were significantly associated with preterm delivery. These findings consisted with the findings of studies done in Ethiopia and that of Agustin Conde and his colleagues but contrary to the studies reported in Nigeria [21, 22]. The difference observed in the results may be explained by intensified nutritional care of mothers soon after delivery, which is commonly depending on local and community practice as a result of early recovery from previous delivery references.

The new ANC model for positive pregnancy experience recommends pregnant women to have a minimum of eight ANC contacts and Tanzanian has adopted this recommendation in its guidelines. This is a goal-centered approach model between the client and healthcare providers and has been shown to improve maternal and perinatal outcome. Pregnancy monitoring tends to be inadequate in sub-Saharan countries due to a lack of an effective perinatal health care system. This study found that the few number of ANC follow-up could have led to preterm delivery. These findings are similar to what was reported in previous studies done in Zimbabwe, Tanzania , Nigeria and Ghana [23- 25].

Urinary tract infection is the most common bacterial illness that occurs during pregnancy. Preterm birth was linked to mothers with a positive history of urinary tract infection in this study, which was comparable to findings reported in studies conducted in Iran, Ethiopia, Kenya, and Nigeria [26- 29]. This could be due to the fact that infection can cause the release of inflammatory chemokines, microbial endotoxins, and cytokines like interleukins and tumor necrosis factors, which stimulate the production of prostaglandins and matrix-degrading enzymes, which then stimulate uterine contractions, resulting in preterm birth [30].

The study found that anemia in pregnancy was not associated with an increased risk of preterm delivery similar to other studies reported in Kenya and Nigeria. However, the findings of this study were contrary to other studies reported in China, Malawi, and Ethiopia [31- 35]. This may be explained by the different in antenatal health related program approach, availability of iron and folate supplements, and local nutrition status as this may contribute to the reduction of complications caused by anemia including preterm delivery.

In this study, preterm delivery strongly correlated with obstetric complications of the index pregnancy. This study found that pregnancy related hypertensive disorder was significantly associated with an increased risk of preterm delivery, consistent with studies reported in Debramarkos town health institutions, Gond town health institutions, and other places in Ethiopia. This can be explained by the fact that pregnancy-related hypertension can influence placental vascular injury, which can then trigger a cascade of uterine contractions, resulting in premature birth.

Antepartum hemorrhage (APH) and pregnancy outcomes in various areas showed to be associated with a higher rates of preterm delivery. Like other reports in Cameroon, Ethiopia, and Tanzania, this study also found that APH was significantly associated with preterm delivery. This is mostly because APH frequently results in an early birth due to the risk it poses to both the expectant mother and the fetus. This study found that mothers who had experienced preterm premature rupture of membranes were significantly associated with an increased risk of preterm delivery. This finding is similar to other studies conducted in Cameroon, Ethiopia, Ghana, Nigeria and in Kenya, [36]. This can be explained by the fact that premature membrane rupture increased fetal plasma interleukin-6, which can precipitate preterm labor and delivery.

In this study, multiple pregnancies were found to be a significant factor associated with increased risk of preterm delivery. Other reports in Northern Eastern Tanzania, Nigeria, Iran, Ethiopia, Kenya, Ghana, and the Democratic Republic of Congo reported similar outcomes [37].The possible reason may be because multiple pregnancy has been associated with other pregnancy- related complications which if not addressed end up with preterm delivery.

Limitations of the Study

The study was conducted based only on one institution source which could result in over or under reporting, which could not be generalized. Furthermore, only live birth mothers and their newborns were included in the study, which may have resulted in an underestimation of the proportion

Conclusion

Preterm delivery is still a public health concern and a serious problem in both obstetric and pediatric care at tertiary hospitals in Tanzania which must be addressed to reduce perinatal mortality. History of preterm delivery, short interpregnancy interval, ANC visits of less than four, preterm PROM, pregnancy-related hypertensive disorders, multiple pregnancies, antepartum hemorrhage and urinary tract infection are independent factors associated with preterm delivery. To reduce the risk of preterm delivery, all at-risk pregnant women should receive more intensive prenatal care. Useful checklists and screening tool need to be improved which will help to identify all women with higher risk of developing preterm delivery.

Abbreviations

MNH: Muhimbili National Hospital; MUHAS: Muhimbili University of Health and Allied Science; KCMC: Kilimanjaro Christian Medical Centre; APH: Antepartum Hemorrhage; NC: Antenatal care; DM: Diabetic Mellitus; GDM: Gestation diabetic mellitus; Hb: Hemoglobin; HTN: Hypertension; HIV; Human immunodefiency virus; PIH: Pregnancy Induced Hypertension ; PPROM: Preterm pre labor rupture of membrane ; PTB: Preterm birth; PTD: Preterm delivery; SDGs :Sustainable Development Goals ; SPSS: Statistical Package for Social Sciences ; UTI: Urinary tract infection ; WHO: World Health Organization; CI: Confidence interval, COR: Crude odds ratio; AOR, Adjusted Odds ratio.

Acknowledgement

First and foremost, we appreciate the Almighty God for providing me with strength and courage throughout my field study, as well as his guidance in assisting us in completing our research. Second, we want to express our sincere gratitude to all professors, specialists, and other academic staffs in the department of Obstetrics and Gynecology at Muhimbili University, who from time to time offered positive inputs that greatly improved our work.

We would also like to acknowledge and extend our sincere gratitude to the administration of Muhimbili National Hospital for their permission to conduct a study at their hospital. We would like to send our sincerely thanks to the Tanzania Ministry of Health for financial support and sponsorship of the entire conduction of this study.

Funding

This study was fully funded by Tanzania government through the Ministry of Health through as a part of its initiative to support health-related programs. The funding institute did not involve in any steps of this study

Ethical Approval and Consent to Participate

Ethical clearance of the study was obtained from MUHAS Senate of Research Publication Committee. Permission to conduct the study was obtained from MNH Authoritys. Only women who gave informed consent were recruited to participate in the study.Mothers with preterm delivery during the study were given care and health education on the factors associated with preterm delivery and how to handle their preterm babies . All participants were fully informed about the research and their rights to participate or withdraw from the study. Privacy and confidentiality were assured to all study participants and the study findings will be widely disseminated to the stakeholders involved in this study.

Conflict of interest

We declare that there was no conflict of interest in this study.

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