|Year : 2017 | Volume
| Issue : 2 | Page : 41-47
First trimester body mass index and pregnancy outcomes: A 3-year retrospective study from a low-resource setting
Idris U Takai1, Ifesinachi J Omeje1, Aliyu S Kwayabura2
1 Department of Obstetrics and Gynaecology Bayero University/Aminu Kano Teaching Hospital, Kano, Kano State, Nigeria
2 Department of Obstetrics and Gynaecology, State Specialist Hospital, Maiduguri, Borno State, Nigeria
|Date of Web Publication||4-Apr-2018|
Dr. Idris U Takai
Department of Obstetrics and Gynaecology, Bayero University, Kano/Aminu Kano Teaching Hospital, Kano, PMB 3011, Kano State
Source of Support: None, Conflict of Interest: None
Background: Extremes of body mass index (BMI) are associated with adverse pregnancy outcomes. This study was conducted to determine the prevalence of obesity and underweight among women in their first trimester and evaluate the impact of first trimester BMI on pregnancy outcome.
Patients and Methods: Pregnant women who booked in the first trimester of pregnancy in Aminu Kano Teaching Hospital, and met the inclusion criteria, were studied retrospectively for a 3-year period from January 2012 to December 2014. Their booking BMIs were calculated and categorized using WHO classes. Pearson's Chi square test was used for all categories.
Results: A total of 649 pregnant women booked in the first trimester during the study period, out of which 502 were eligible for the study. Of this, 99 women were obese and 57 were underweight giving the prevalence of obesity and underweight in first trimester of pregnancy as 15.3% and 8.8% respectively. Maternal outcomes mostly associated with obesity and overweight were hypertensive disorders in pregnancy (42.0%), gestational diabetes mellitus (41.3%), increased abdominal and instrumental delivery (38.6%), as well as third and fourth degree perineal tears (71.4%). Neonatal outcomes were low birth weight and fetal macrosomia (57.8%), preterm delivery and prolonged pregnancy (46.0%). The underweight group had a favorable outcome in majority of the outcomes assessed.
Conclusion: Obesity in pregnancy is relatively common in our environment and is associated with adverse fetomaternal outcome when compared to the underweight subjects. There is a need for preconception care and further research to identify and possibly mitigate the risk factors of obesity.
Keywords: Body mass index, booking, first trimester, pregnancy outcome
|How to cite this article:|
Takai IU, Omeje IJ, Kwayabura AS. First trimester body mass index and pregnancy outcomes: A 3-year retrospective study from a low-resource setting. Arch Int Surg 2017;7:41-7
|How to cite this URL:|
Takai IU, Omeje IJ, Kwayabura AS. First trimester body mass index and pregnancy outcomes: A 3-year retrospective study from a low-resource setting. Arch Int Surg [serial online] 2017 [cited 2018 May 20];7:41-7. Available from: http://www.archintsurg.org/text.asp?2017/7/2/41/229190
| Introduction|| |
In the past, obesity was alien to the developing countries of the world but it is increasingly attaining epidemic level in recent times.,,, Obesity is now seen as a pandemic ,,, and was recently described by the World Health Organization (WHO) as one of the most blatantly visible but most neglected public health problems ,,, that threatens to overwhelm both developed and developing countries.,,,, This trend is also obtainable amongst pregnant women in both developing and developed countries, and may be attributed to the effects of westernization such as increased consumption of diet rich in refined sugars and saturated fats as well as increased physical inactivity and alcohol intake.,,,,,, For example, in the UK about 18.5–20% of pregnant women are obese., In the USA, 18.5–38.3% of pregnant women are obese and about 28–48% are overweight.,
Undernutrition with the consequent underweight is still prevalent in developing countries, leaving these parts of the world with the consequences of both obesity and underweight.,,, In India for example, obesity was reported in about 12.6% of pregnant women, with 21.04% being overweight and 14.79% being underweight in a nationwide study. In Nigeria, the prevalence of obesity and overweight in pregnancy has been reported respectively to be 33.1% and 32.5% in North-Central regions; 10.7–22.6%, and 14%, in Southeast; 9.63%, and 50.7% in the South-South; and 12.6% and 20.3%, in Southwestern part of the country. Amongst Utah women of southwest Nigeria, about 7.3% were reported to be underweight.
Definitions of overweight, obesity, and underweight differ in different reports. In order to classify different weight categories, some researchers use the waist-hip ratio; an absolute weight; or a weight gain in pregnancy. Others use body mass index (BMI), which is now widely accepted as a better measure of over or underweight.,, A BMI of less than 18.50 kg/m 2 is considered underweight while one between 25 kg/m 2 and 29.99 kg/m 2 is overweight.,, BMIs of 30 kg/m 2 and above is classified as obesity.,, When measured before pregnancy, this pre-pregnancy BMI is used as the standard against which measurements are made in pregnancy since pregnancy is associated with increased weight gain from the fetus, placenta, and liquor, as well as changes in the uterus, breast, blood, extracellular fluids, and fats., When prepregnancy BMI is not measurable or not available, first trimester BMI can be used since weight gain in first trimester is negligible.,,
An increased association of morbidity and mortality with obesity is well established in both nonpregnant and pregnant women reflecting an increased risk of medical, surgical, or anesthetic complications.,, Obesity confers a high-risk status to pregnant women in particular, and a high proportion of women who die in pregnancy or postpartum are obese.,,,, The confidential enquiry into maternal death  reported that 35% of all maternal deaths in 2000-2002 were obese women having BMI ≥ 30kg/m 2.
Antenatally, obesity increases the risk of gestational diabetes mellitus, gestational hypertension, thromboembolism, and pre-eclampsia.,,, It is also associated with other risks, including urinary tract infection (UTI), preterm labor, prolonged pregnancy, and antepartum hemorrhage.,,,, During the intrapartum period, obesity is associated with poor labor outcomes and induction of labor.,, Obese women are less likely to achieve a normal delivery, have increased risk of cesarean section.,,, In the postnatal period, obese women are less likely to breastfeed successfully, they have a longer postnatal stay in the hospital and are at increased risk of postnatal infection.,,, Long-term consequences of obesity also exist. Obese women tend to further increase in weight with each subsequent pregnancy and are more likely to remain obese with all the attendants risk associated with obesity., More so, children of obese mothers are likely to become obese later life and are more at risk of type II diabetes mellitus and its sequalae.,
Other adverse neonatal outcome associated with obesity include miscarriages, stillbirth, congenital anomalies, and neonatal intensive care admission.,,, Others include low 5-minute APGAR score, fetal macrosomia, abnormal lie, and malpresentation and neonatal deaths.,.
In comparison, the effect of maternal underweight on obstetric outcome is uncertain. While some studies show an increase in preterm delivery, low birth weight, miscarriages, anemia, and stillbirths,,, others report a protective effect on certain pregnancy complications and interventions.,,
This study adds to the literature on the subject, and reports on indices for which we have no recent values for Kano, Nigeria. Also, this study population will be more representative of the general population in our environment since Aminu Kano Teaching Hospital (AKTH) serves as the referral Centre for the North West and some of the North East regions. The study was therefore conducted to determine the prevalence of obesity and underweight and evaluate the impact of first trimester BMI on pregnancy outcome in patients attending AKTH.
| Patients and Methods|| |
This was a 3-year retrospective study of women in the first trimester of pregnancy who booked for antenatal care (ANC) in Department of Obstetrics and Gynaecology of AKTH, Kano, Nigeria from January 2012 to December 2014. AKTH is a 500 bed tertiary health institution serving Jigawa, Katsina, Zamfara, Kebbi, Kaduna, and Sokoto states in Northwestern Geopolitical zone of Nigeria. The 2014 AKTH annual report put its ANC attendance and delivery rates at 4000 and 5000 respectively.
Kano State lies between latitude 12°00 North and longitude 14°31 East. It is the second largest city and is located in Northern Nigeria. According to 2006 population census, the population of Kano city was 2,282,861 and for the entire state was put at 9.6 million.
The ethical clearance was obtained from the Research and Ethical Committee of AKTH. Following ethical approval, the booking register for this period was retrieved from the health records department of Obstetrics and Gynaecology of AKTH from which the patients' names and hospital numbers were obtained. Only pregnant women booked in the first trimester were included in the study since weight gain in first trimester is negligible ,, and other trimesters are associated with significant weight gain from the fetus, placenta, and liquor, as well as changes in the uterus, breast, blood, extracellular fluids, and fats., The gestational age at booking was gotten either from the recorded last menstrual period when available or from the early ultrasound scan. Among those who booked in the first trimester, those with incomplete data as well as high-risk patients were excluded, including those with multiple pregnancies, previous cesarean section and those with chronic medical conditions such as chronic hypertension, pregestational diabetes mellitus, and sickle cell disease patients. Those in whom episiotomies were performed were also excluded since perineal tear, second degree inclusive which is like episiotomy was one of the maternal outcomes assessed for.
The booking register was used to retrieve the medical case records of those who met the inclusion criteria for the study. From these records, sociodemographic data (age, parity, ethnic group, and occupation) and maternal anthropometric data (weight in kg and height in meters) were obtained. The maternal anthropometric data were used to calculate the BMI in kg/m 2. The BMIs are grouped into six according to WHO classification.
Underweight: <18.50 kg/m 2
Normal weight: 18.50–24.99 kg/m 2
Overweight: 25–29.99 kg/m 2
Obesity 1: 30–34.99 kg/m 2
Obesity 2: 35–39.99 kg/m 2
Obesity 3: Greater than or equal to 40 kg/m 2
The group with the BMI in the normal range (18.50–24.99) was used as the reference group for analysis. The maternal outcomes assessed included hypertensive disorders in pregnancy, gestational diabetes mellitus, prolonged labor, cesarean section, instrumental vaginal delivery, perineal tear, and primary postpartum hemorrhage while the fetal/neonatal outcome assessed included miscarriage, preterm delivery, prolonged pregnancy, fetal macrosomia, low birth weight, APGAR score <7 in the 5th minute and early neonatal deaths.
Microsoft Excel for MAC 2011 was used for all mathematical calculations and data entry, and analysis was done using SPSS version 20, (SPSS Inc, Chicago, IL USA). The descriptive statistics was done where necessary and Chi square test was used to identify association between qualitative variables and BMI. P value <0.05 was considered as statistically significant. Results were presented in tabular forms.
| Results|| |
A total of 649 pregnant women were booked for their antenatal care in the first trimester during the study period, out of which 502 (77.3%) were eligible for the study. The mean maternal height was 1.62 m ± 0.08, the mean maternal weight was 66.108 kg ± 16.78, the mean maternal BMI was 25.077 kg/m 2 ± 6.1, and the mean maternal age was 25.89 years ± 5.4, ranging from 16 years to 45 years. Of this number eligible for the study 57 (11.4%) cases were underweight, 229 (45.6%) were of normal weight, 117 (23.3%) were overweight, and 99 (19.7%) were obese. The prevalence of obesity and underweight were thus 15.3% and 8.8% respectively. Obesity was associated with maternal age ≥36 years (75.9%), non Hausa-Fulani ethnic group (54.5%), grand multiparity (72.4%), and amongst civil servants (49.1%) P value = 0.0001 and no association with clinical risk was found among the underweight/normal weight (non-obese) as shown in [Table 1].
[Table 2] shows the socio-demographic characteristic of the study population. Majority (64.3%) of the cases were between 21 years and 30 years and majority were para 0-4, (94.2%) about two-third (71.4%) of the study population were of Hausa-Fulani ethnic group, more than half (52.0%) were housewives and 45.6% had normal weight.
Maternal outcomes for the different BMI categories are shown in [Table 3]. Increased cesarean section rate and instrumental delivery were seen in obese (38.6%) and overweight (30.0%) groups compared to those with normal weight (28.6%). It was lowest amongst the underweight (2.9%), (P = 0.010). All degrees of perineal tears were commoner among cases with normal weight (39.2%), closely followed by the overweight group (30.4%). It was similar amongst obese (15.7%) and the underweight (14.7%) groups, (P = 0.0001).
Primary postpartum hemorrhage was commoner in those with normal weight (37.0%) than the obese (30.7%), the overweight (27.6%), and the underweight (4.7%), (P = 0.0001). Hypertensive disorders in pregnancy were commoner in the obese (42.0%). 28.4% of overweight women, 24.7% of pregnant women of normal weight, and 4% of underweight women suffered these disorders, (P = 0.0001). Gestational diabetes mellitus was seen more in the obese (41.3%), followed by the overweight (28.3%). It was least seen among the underweight (4.3%), with 26.1% of normal weight pregnant women having the condition (P = 0.0001). Differences in packed cell volume and duration of labor were not statistically significant across the categories.
Fetal outcomes for the different BMI categories are shown in [Table 4]. Abnormal fetal weight (weight <2.5 kg and those ≥4 kg) were seen more (57.8%) in overweight/obese group compared to those with normal weight (35.9%) or underweight group (6.3%) (P = 0.031). Also, preterm and postdate pregnancy (<37 weeks and >40–42 weeks respectively) were increased (46.0%) in overweight/obese group compared to women with normal weight (42.1%) or underweight women (11.9%) (P = 0.048). Fifth minute APGAR score and miscarriage, and early neonatal death were not statistically significant across the BMI categories.
| Discussion|| |
The result of this study emphasizes obesity as an emerging pandemic amongst pregnant women, and Kano state is not spared. The prevalence of 15.3% reported in this study is comparable to previously published data in Nigeria and India., This is not surprising as Kano state, being a merchant city, is a melting pot of all ethnic groups in Nigeria, as well as non-Nigerians. AKTH serves as a referral center for most states within the northwest region, and so, values are expected to be representative of the wider Nigerian population.
The prevalence of obesity reported in this study; however, is slightly lower than what has been documented in some studies in the western world., This is not surprising as majority of the Nigerian populace still live in the low resource settings and below poverty line, as Nigeria is still classified as a developing country.
The prevalence of overweight pregnant women in this study is similar to result of other studies within and out of Nigeria.,, The prevalence of underweight in this study, though similar to that seen in southwest Nigeria,, is however, lower than that seen in North Central Nigeria  and outside Nigeria, including India. This might be an incidental finding and may need further exploration.
In this study obesity was associated with increased parity, age ≥36 years, and non-Hausa/Fulani ethnicity. Multiparty is associated with obesity since not all weight gained during pregnancy is lost after delivery, and patient gains weight in subsequent pregnancies. Increasing age associated with obesity may be related to parity increasing with age, as a woman is more likely to be parous the older she gets. The finding of higher prevalence of obesity among the non-Hausa/Fulani ethnic group might be dietary as they are more likely to adopt western diets, which is known to consist more of refined sugar and saturated fats than fiber.,
This study also identified civil servants to be more at risk of being overweight or obese. This may be attributable to the sedentary nature of their professions (longer sitting periods), long periods spent at work, as well as an increased likelihood to consume “junk food” including soda drinks and pastries. These soda drinks and frequent snacking on pastries have been shown to be associated with increased weight gain.
This study also shows that maternal obesity and overweight are associated with adverse obstetric outcomes. The significant association between being overweight or obese in pregnancy, and hypertensive disorders and gestational diabetes mellitus in pregnancy seen in this study is similar to previously published data.,,,,,,,,,,,,,,,,, Increased cesarean section rate and a recourse to instrumental delivery were also seen in these two groups compared to those with normal weight or those that were underweight, probably due to increased medical disorders in these patients, and the increased fetal macrosomia that predisposes to cephalopelvic disproportion.
That all degrees of perineal tears were more common amongst normal weight individuals may be related to less attention paid to low-risk patients in labor, and not their BMI category, as multiple women undergo labor concurrently, and with the manpower challenges prevalent in the Nigerian health sector and in AKTH, effective attention per woman is limited. This is compared to obese or overweight women, who have the attention of the attending doctor in labor thereby preventing perineal tears. Among the obese women that had perineal tear; however, majority (71.4%) had 3rd to 4th degree tears. This trend is similar to observations documented in literature ,, and could be due to increased frequency of fetal macrosomia or instrumental vaginal delivery.
Primary postpartum hemorrhage was significantly increased in those with normal weight. This is surprising as several studies document increased primary postpartum haemorrhage in the overweight or obese.,,,,,,,,,, This is probably due to less attention paid to this category in labor as highlighted earlier.
In this study, those who were overweight and obese delivered more low birth weight and macrosomic babies. This trend is similar to observations documented in literature ,,,,,,,,,, and may be due to an increased risk of diabetes mellitus and hypertensive disorders in pregnancy in this group also. These co-morbidities may predispose to fetal macrosomia and/or intrauterine growth restriction.
The preterm and postdate pregnancy was also significantly increased in the overweight and obese group. Similar findings are reported in the literature.,,,,, The increased risk of preterm delivery in the obese may be iatrogenic, as increased prevalence of medical conditions in the mother or fetal macrosomia and intrauterine growth restrictions of the baby may warrant early interception by attending physicians. Increased low birth weight, stillbirth, and spontaneous preterm delivery might also be due to dysregulation of proinflammatory cytokines as well as increased risk of infection in obese and overweight individuals as they will lead to reduced placental surface area and also their vasculature with consequent uteroplacental insufficiency.
Low 5th minute APGAR score, miscarriages, and early neonatal death were all more common in the obese and overweight group, similar to the literature.,
In this study, being underweight appeared to confer more favorable maternal and fetal outcomes. This is probably because some of the outcome measures and BMI categories were merged so as to get valued results and underweight was left to stand alone since it cannot be merged scientifically with other BMI categories. Our finding also follows similar findings in the literature and they were attributed to the way BMI was calculated using self-reported weight and height and not the rigorous anthropometric measurement.,, This self-reported weight and height may have caused under or over reporting of their weight and height and may have led to misclassification of BMI hence leading to inconsistent conclusions. Other studies show an increase in preterm delivery, low birth weight, miscarriages, anemia, and stillbirths and they were attributed to under nutrition and consequent increased risk of infection also, uteroplacental insufficiency resulting from low cardiac output and increased peripheral resistance seen in these group of individuals.,,
Our retrospective study may have been limited with problems of data storage and retrieval. The short duration of the study (3 years) may not reflect the changing trends in population of pregnant women adequately and so the subject needs to be studied prospectively for a longer period. Some of the outcome measures assessed and BMI categories were scientifically merged in order to get valued results, this may have shown a better reflection of the findings if left to stand separately.
| Conclusion|| |
Obesity and underweight in early pregnancy is high in Kano state and its environs. While underweight had a protective effect on most of the outcomes assessed, obesity and overweight were associated with adverse fetomaternal outcomes. Normal weight pregnant women can also be associated with adverse outcomes when they are not properly managed, therefore need adequate management to remain healthy. Obesity was found to be associated with increased parity, age ≥36 years, non-Hausa Fulani and being a civil servant; however, no association was found with underweight. This warrants further study.
Preconception care including good and adequate diet, weight loss, exercise as well as family planning to reduce family size and also to enhance proper child spacing is advocated for all obese and overweight women so as to minimize risks and its associated consequences. Further research is required to identify the risk factors of obesity and ways of mitigating them. A prospective study on this subject matter is needed to obviate the limitations associated with data storage and retrieval.
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Conflicts of interest
There are no conflicts of interest.
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[Table 1], [Table 2], [Table 3], [Table 4]