Key Words
Meitei - preterm birth - menarche - tobacco consumption - socioeconomic
Introduction
Preterm birth (PTB), <37 weeks of gestation, is one of the world's leading causes
of death in children under 5 years of age. It increases the risk of high mortality
and lifelong impairment.[1] It is estimated to be a risk factor in at least 50% of all neonatal deaths.[2] More than 60% of the total PTBs occur in Africa and South Asia. In low-income countries,
12% of babies are born too early, which is comparatively higher than in high-income
countries (9%). Studies reported an increasing trend in PTB rates over the past two
decades, specifically from low- and middle-income countries.[3] In India, the prevalence of PTB varies significantly from 6.1% in Maharashtra to
28.25% in Tamil Nadu.[4]
[5] India contributes 23.4% of the global PTB.[6] The PTB affects both the mother and the children with an increased risk of developing
short- and long-term chronic noncommunicable diseases.[7] Identifying the causes of PTB is one of the major areas of research to prevent PTB
and its associated adverse health outcomes. The occurrence of PTB has been linked
with multiple factors such as genetic, pregnancy-induced chronic diseases (hypertension,
diabetes), infections, early induced labor, multiple gestations, anemia, antenatal
care visits, age at menarche, etc.[8] Moreover, socioeconomic factors of the mother are associated with the occurrence
of PTB, including less maternal income, low level of education, occupation, early
childbearing, smoking, and place of residence.[9]
[10]
[11]
[12] However, ethnic differences in the causation of PTB remain. Thus, identifying women
at high risk of PTB at an early pregnancy stage may allow timely intervention against
PTB and future life-threatening health events.[13]
The epidemiology of PTB has not been explored in most of the Indian population. Moreover,
existing studies are concentrated only in some specific states, with limited studies
predicting risk factors contributing to PTB.[8] However, studies on PTB have been lacking among the Northeast Indian populations.
A limited study has been performed reporting the association of PTB with maternal
low hemoglobin levels during pregnancy and also claimed risk of low birth weight among
PTB babies.[14] Thus, a preliminary study was conducted to determine the prevalence and correlate
PTB with socioeconomic factors among the Meitei women of Manipur, Northeast India,
to understand the population-specific PTB prognosis.
Materials and Methods
Design, Population, and Setting of the Study
A community-based cross-sectional study was conducted among the postpartum Meitei
women of Manipur, Northeast India. Women from the Meitei ethnic group, with an East
Asian Ancestry, residing in urban and rural areas were recruited in the present study
from October 2019 to January 2020. In this study, two districts, Imphal East and Imphal
West, were selected considering the poor reproductive health conditions per the reports
of the National Family Health Survey, Manipur. The highest burden of anemia and increased
rate of early childbearing age were reported in Imphal West. In contrast, Imphal East
reports the worst performing district for inadequate antenatal care during the first
trimester.[15]
Postpartum women that gave birth to a singleton live-born infant and women who are
residing permanently in the area and willing to participate in the study were included
in the present study. Women with twin pregnancies, cognitive and physical limitations,
and those unwilling to participate were excluded from the study.
Variables
All the information was collected through a structured interview schedule consisting
of questions on socioeconomic characteristics such as age at conception, gestational
age, educational level, occupation, income, place of residence, and social category
(unreserved or schedule caste) were assessed after obtaining informed written consent.
Information on mother menarche age (<13 years or ≥13 years), antenatal care visit
(less than four visits and four or more visits), family history of PTB (either maternal
or paternal), and tobacco consumption/chewing during pregnancy was also obtained through
the interview. Data on the mother's age at conception were obtained with childbearing
ages of <20 years and ≥20 years. Regarding maternal occupational status, women with
no current occupation but managing household affairs and doing housework were categorized
as housewives, while women engaged as artisans, laborers, manual work, and physical
exertion-related work as full-time workers.
Data Analysis
The data collected were initially transferred to MS Excel software and coded, and
further statistical analyses were performed using Statistical Package for Social Sciences
25 version. The prevalence of PTB was calculated in the studied community. Univariate
analysis was performed to determine the association of socioeconomic variables with
PTB. The significant variables as observed in the univariate analysis were further
adjusted to perform the multivariate analysis using logistic regression. Statistical
significance was taken based on a p-value <0.05.
Results
The overall prevalence of PTB was 23.01%. Of the different types of PTB, moderate-to-late
preterm comprised 55.17%, very preterm 31.03%, and extremely preterm 13.79%. Socioeconomic
characteristics revealed that mothers with a monthly income of less than 10,000 rupees
were significantly more common in the preterm group than in the term group (41.37
vs. 20.61%, p = 0.024). Low-income mothers were 2.7 (odds ratio [OR] = 2.72, 95% confidence interval
[CI]: 1.12–6.60, p = 0.024) times more likely to experience PTB than high-income mothers.
Similarly, full-time working women were found quite frequently in the preterm group
than in the term group (41.37 vs. 18.55%), with 3.10 times more likely to deliver
PTB than the housewife mothers (OR = 3.10, 95% CI: 1.26–7.61, p = 0.011). Moreover, mothers who consumed tobacco were more likely to experience PTB
than those who did not (OR = 3.03, 95% CI: 1.28–7.15, p = 0.01). Regarding the educational level, there were significantly more women with
illiteracy and elementary education in the preterm group than in the term group (65.52
vs. 43.29%, p = 0.036). Mothers with a family history of PTB were 2.84 times more likely to give
preterm delivery than their counterparts (OR = 2.84, 95% CI: 1.20–6.72, p = 0.015). The proportion of mothers with early menarche was significantly higher
among the preterm groups than in the term group (55.17 vs. 29.89%, p = 0.013). The analysis also showed that the chances of giving PTB were significantly
higher among the mothers who visited fewer antenatal check-ups during pregnancy than
those with adequate antenatal care (ANC) visits (51.72 vs. 28.86%, p = 0.023). Most of the mothers delivering PTB children resided in rural areas (86.20%)
and had early childbearing age (34.48%) than the mothers who gave term birth. However,
no statistically significant difference was observed between the two groups (p > 0.05). The social category of the mother did not show any significant differences
between the unreserved category and schedule caste group with respect to PTB (p = 0.372; [Table 1]).
Table 1
Distribution of socioeconomic characteristics of Meitei women in preterm and term
groups
|
Socioeconomic characteristics
|
Birth
|
p-Value
OR
CI
|
|
Preterm
(29, 23.01%)
|
Full-term
(97, 76.9%)
|
|
No.
|
%
|
No.
|
%
|
|
Mother's income (per month)
|
|
Less than 10,000
|
12
|
41.37
|
20
|
20.61
|
p = 0.024
OR = 2.72
CI = 1.12–6.60
|
|
More than 10,000
|
17
|
58.62
|
77
|
79.38
|
|
Mother's occupation
|
|
Housewives
|
17
|
58.62
|
79
|
81.44
|
p = 0.011
OR= 3.10
CI = 1.26–7.61
|
|
Full time workers
|
12
|
41.37
|
18
|
18.55
|
|
Tobacco consumption (during pregnancy)
|
|
No
|
11
|
37.93
|
63
|
64.94
|
p = 0.010
OR = 3.03
CI = 1.28–7.15
|
|
Yes
|
18
|
62.06
|
34
|
35.05
|
|
Level of education
|
|
Illiterate and elementary
|
19
|
65.52
|
42
|
43.29
|
p = 0.036
OR = 0.40
CI = 0.17–0.95
|
|
Higher secondary and above
|
10
|
34.48
|
55
|
56.70
|
|
Age at menarche
|
|
|
|
|
|
|
Less than 13 y
|
16
|
55.17
|
29
|
29.89
|
p = 0.013
OR = 0.35
CI = 0.15–0.81
|
|
More than 13 y
|
13
|
44.83
|
68
|
70.10
|
|
Childbearing age
|
|
< 20 y
|
10
|
34.48
|
23
|
23.71
|
p = 0.247
OR = 1.69
CI = 0.69–4.15
|
|
≥ 20 y
|
19
|
65.51
|
74
|
76.28
|
|
Social category
|
|
Unreserved
|
20
|
68.96
|
58
|
59.79
|
p = 0.372
OR = 0.67
CI = 0.28–1.62
|
|
Scheduled caste
|
9
|
31.03
|
39
|
40.20
|
|
Place of residence
|
|
Rural
|
25
|
86.20
|
67
|
71.27
|
p = 0.102
OR = 2.54
CI = 0.81–7.96
|
|
Urban
|
4
|
13.79
|
30
|
30.92
|
|
Antenatal care (ANC)
|
|
Less than four visits
|
15
|
51.72
|
28
|
28.86
|
0.023
OR = 0.38
CI = 0.16–0.89
|
|
More than four visits
|
14
|
48.27
|
69
|
71.13
|
|
Family history of preterm births
|
|
No
|
15
|
51.72
|
73
|
75.25
|
0.015
OR = 2.84
CI = 1.20–6.72
|
|
Yes
|
14
|
48.27
|
24
|
24.74
|
Abbreviations: CI, confidence interval; OR, odds ratio.
We further performed multivariate analysis using logistic regression to investigate
which socioeconomic factors were the best predictors of PTB after adjusting the factors
like the mother's income, education, occupation, tobacco consumption, antenatal care,
age at menarche, and family history of PTB ([Table 2]). The most significant risk observed in the study was the mother's occupation; full-time
workers showed greater odds of having PTB (adjusted odds ratio [AOR] = 4.46, 95% CI:
1.40–14.26, p = 0.012) compared with housewife mothers. Early age at menarche revealed a significant
association with PTB, with 4.26 times more likely to deliver preterm (AOR = 4.26,
95% CI: 1.49–12.12, p = 0.007). The present study also found that those with a family history of PTB had
a threefold increased risk of delivering PTB (AOR = 3.14, 95% CI: 1.09–9.04, p = 0.034). Women who consumed tobacco during pregnancy were 2.90 times more likely
to experience delivering PTB than mothers who did not with a statically borderline
significant difference (AOR = 2.90, 95% CI: 1.01–8.33, p = 0.048). Notwithstanding this, women with less than four antenatal visits and those
with lower educational levels showed a more than twofold increased risk of giving
PTB. However, both predictors were statically insignificant after adjusting the risk
factors in multivariate logistic regression analysis (p > 0.05).
Table 2
Association between socioeconomic factors and PTB in multivariable logistic regression
analysis
|
Socioeconomic characteristics
|
OR[a] 95% CI
|
p-Value
|
|
Mother's income
|
|
More than 10,000
|
Ref
|
p = 0.022
|
|
Less than 10,000
|
0.28(0.10–0.84)
|
|
Mother's occupation
|
|
Housewives
|
Ref
|
p = 0.012
|
|
Full time workers
|
4.46(1.40–14.26)
|
|
Tobacco consumption
|
|
No
|
Ref
|
p = 0.048
|
|
Yes
|
2.90(1.01–8.33)
|
|
Level of education
|
|
Higher secondary and above
|
Ref
|
p = 0.116
|
|
Illiterate and elementary
|
2.30(0.81–6.51)
|
|
Antenatal care (ANC)
|
|
More than four visits
|
Ref
|
p = 0.169
|
|
Less than four visits
|
2.05(0.74–5.73)
|
|
Family history of preterm birth
|
|
No
|
Ref
|
p = 0.034
|
|
Yes
|
3.14(1.09–9.04)
|
|
Age at menarche
|
|
|
|
More than 13 y
|
Ref
|
|
|
Less than 13 y
|
4.26(1.49–12.12)
|
p = 0.007
|
Abbreviations: CI, confidence interval; OR, odds ratio; PTB, preterm birth.
a Adjusted for mother's income, occupation, tobacco consumption, level of education,
age at menarche, antenatal care, and family history of preterm births.
Discussion
PTB is considered one of the major health issues of birth outcomes throughout the
world, which is also the leading cause of death in children under 5 years of age.
More than 15 million babies are born preterm yearly, accounting for approximately
more than 1 in every 10 babies. The PTB rate has increased specifically in low- and
middle-income countries in the last two decades. Previous studies reported that there
is a lack of reliable information on the prevalence of PTB in most of the developing
country.[3]
[16] In India, studies on PTB are mainly concentrated in some specific states. The present
findings showed a high prevalence of PTB, 23.01%, higher than the global prevalence
across 184 countries ranging from 5 to 18%.[16] The PTB rate is also found to be higher than in other studies reported from Zimbabwe,
Malawi, and Kenya.[17]
[18]
[19] In India, studies on PTB report varied prevalence rates across different geographical
regions.[12] The current finding also reports higher rates of PTB than previous studies as reported
from Gujarat (9.0%), Maharashtra (6.1%), and Tamil Nadu (5.6%).[5]
[20]
[21] Although the high prevalence of PTB in the present study is in accordance with some
groups of the Indian population, it suggests a high prevalence of PTB in the Indian
population.[4]
[11]
[12] Of the overall prevalence of PTB, 13.79% are extremely preterm. Such a high alarming
prevalence of PTB highlights the need for urgent attention, monitoring, regulation,
and intervention of PTB at the population level throughout the country. It will become
one of India's major public health burdens if not intervened in time.
Regarding the risk factors of PTB, previous studies have identified several potential
predictors of PTB.[8] The current study shows a significant association between a mother's income and
PTB occurrence. It supports previous studies in which mother with low monthly income
was more likely to give birth to preterm infants.[22] However, the inconsistent finding was also reported from Qatar, suggesting no positive
association between a mother's low income and the occurrence of PTB.[9] The education level of mothers has an impact on their pregnancy outcomes. It is
claimed that the mother's education level was a strong predictor of PTB. In the study,
mothers with lower educational levels have more than twofold increased risk of delivering
PTB babies (AOR = 2.30 95% CI: 0.81–6.51). However, it does not reveal statistical
significance (p = 0.116). It could be because of the lack of proper educational awareness on maternal
health and related pregnancy outcomes among the term group with higher education levels.
It is explained by the constitution of 23.63% of mothers reporting inadequate antenatal
care visits among the term mothers with higher secondary and above education levels.
No association between the mother's education level and PTB is supported by the previous
studies.[9]
[23] However, different studies also reported inconsistent results suggesting the mother's
lower education level is one of the strong predictors of PTB.[24]
[25] It suggests that educational awareness of maternal health and pregnancy outcomes
could be a strong predictive factor of PTB than mothers' education level, particularly
in rural populations of low-middle-developing countries.
It is claimed that the mother's occupation can predict an increased risk for PTB.
Women who performed intensive work during pregnancy had a fivefold increased risk
of having a PTB (AOR = 5.37, 95% CI: 1.39–20.68).[23] This claim is supported by the present study in which women in full-time work were
more likely to give PTB than housewife mothers (AOR = 4.46, 95% CI:1.40–14.26). Studies
conducted in Iran and Italy have also reported consistent findings with the present
study where heavy working women during pregnancy increase the risk of PTB.[26]
[27]
Regarding unhealthy lifestyles, tobacco consumption before or during pregnancy showed
a more than twofold increased risk of PTB in the present study (AOR = 2.90, 95% CI:
1.01–8.33, p = 0.048). It is consistent with the study reporting high odds as seven times more
likely to deliver PTB among the mothers consuming tobacco than the nonuser mothers
(OR = 7.08, 95% CI: 4.14–12.14).[28] Such a significant positive association between tobacco consumption and preterm
delivery is further strengthened by the reports of systematic and meta-analysis studies
among pregnant women in India.[29] The study reveals maternal tobacco use during pregnancy increases the risk for PTB
with a 1.39 pooled odds ratio.
Of the different predictors of PTB, age at menarche has been investigated to predict
the risk of preterm delivery. Various PTB studies across the world report significant
associations between preterm delivery and mother's menarche onset age. This study
reports a significant association between early menarcheal age (mean age 11.5 ± 1.37)
and PTB. Women who had menarcheal age less than 13 years of age are found to have
a 4.26-fold increased risk of preterm delivery among the studied Meitei women population
(AOR = 4.26, 95% CI: 1.49–12.12, p = 0.007). A study on 11,016 Chinese women from the Healthy Baby Cohort between 2012
and 2014 also claims a significant association between age at menarche with PTB (OR = 1.67,
95% CI: 1.18–2.36).[13] No significant association between PTB and age at menarche is also reported in some
studies.[30] So far, there is no concrete evidence, to our best knowledge, on the occurrence
of preterm delivery due to early age at menarche among the Indian population. This
is the first study that reports the risk of preterm delivery in women with an early
menarcheal age among the northeast Indian population. It needs to be validated in
other Indian populations to establish menarcheal age as one of the potential predictors
of PTB.
Receiving antenatal health care services by a mother, particularly during pregnancy,
immensely improves overall pregnancy outcomes. Therefore, inadequate antenatal care
visits become another vital risk factor for PTB. In the present study, mothers who
had inadequate ANC visits were more likely to deliver preterm when compared with those
mothers with adequate ANC visits (p = 0.023). However, after adjusting all the significant confounding factors, no significant
positive association was observed between inadequate ANC visits and preterm delivery.
Similarly, there is no substantial correlation between PTB and the number of ANC visits
from the Gambia and the Belgian population.[31]
[32] However, another study claims a significant positive association between inadequate
ANC visits of the mothers during pregnancy with PTB (AOR = 1.90, 95% CI: 1.13–3.18).[31]
[33] It is further supported by other research findings reporting less than four ANC
visits during pregnancy were significantly associated with an increased risk of delivering
PTB compared with adequate ANC visits.[24]
[34]
Different studies have investigated the association between a mother's family history
of PTB and the risk of preterm delivery. In the study, mothers with a family history
of preterm delivery have a threefold higher risk of PTB than their counterparts (AOR = 3.14,
95% CI: 1.09–9.04). It signifies that women with a family history of PTB either in
maternal or paternal (or both) are at higher risk of preterm delivery. Such a positive
association is supported by other studies reporting a positive association between
a mother's family history of PTB and a higher risk of delivering preterm babies (adjusted
relative risk [aRR] = 1.44, 95% CI: 1.22–1.97).[34]
[35] Such significant positive association results highlight that PTB runs in families.
Moreover, it signifies the inheritance and genetic influence on the duration of gestation,
causing the risk of PTB.
Different studies suggest a significant positive association between maternal childbearing
age and preterm delivery. The risk of PTB increases significantly among teenage mothers
or young maternal age groups.[5]
[24] Mothers less than 20 years were significantly associated with a high risk of PTB.[9] However, the present study does not find any significant association between childbearing
age and preterm delivery. The study supports such inconsistent findings performed
in the Bangladesh population in which women aged <20 years were protective against
PTB.[36] Moreover, a longitudinal cohort study also reveals a reduced risk of preterm delivery
among Canadian mothers aged 30 to 34 years.[37] Such discrepancy in the results could be addressed by conducting population-specific
studies on the differences in PTB risks, such as sociodemographic factors among different
ethnic groups.
In the present study, no significant association was found between the mother's residence
and delivering preterm. This finding agrees with similar studies suggesting no effect
of the mother's place of residence on PTB.[38] In contrast, a cross-sectional study in Uttar Pradesh reported a significant positive
association where women residing in rural areas are more likely to give PTB compared
with urban residents.[11] Inconsistent findings are also reported that urban resident women had an increased
risk of delivering preterm.[39] Such discrepancy might be due to better and easily accessible maternal health services
in urban areas, which increases PTB risk in rural residents. On the contrary, the
high prevalence and increased risk of having PTB among urban residents might be due
to the differential socioeconomic status and lifestyles.[34]
Strengths and Limitations
The present study reveals both strengths and limitations. This study is the outcome
of a community-based study performed through a household survey that minimizes the
selection bias observed in the hospital-based study. This study is the outcome of
preliminary work and the first attempt among the Meitei women of Manipur to determine
population-specific socioeconomic risk factors of PTB. We failed to incorporate a
large sample size and some of the risk factors of PTB, such as previous PTB, pregnancy-induced
hypertension, gestational diabetes, infection during pregnancy, and threatened abortion.
It could be the main limitation of the present study. Despite this limitation, the
present study addresses the high prevalence of PTB and the significant impact of socioeconomic
factors on maternal birth outcomes among Manipur Meitei women, particularly in Northeast
India.
Conclusion
The Meitei women of Manipur, Northeast India, have a comparatively higher prevalence
of PTB. Moreover, the present study highlights the significant correlations between
the mother's socioeconomic factors and PTB. It is a need to understand the differential
socioeconomic patterning with maternal health outcomes and the mechanism underlying
such inequalities. Therefore, studies on PTB should focus on modifiable socioeconomic
predictors to propose early implementation of preventive interventions among pregnant
women who are at high risk for preterm delivery. Such community-specific studies may
help prevent preterm delivery and later risk of cardiometabolic health problems in
mothers. The present study is of the initial research; more in-depth large population-specific
studies covering different risk factors will be needed to replicate and validate the
results to develop population-specific interventional strategies.
