RESEARCH ARTICLE
Blood pressure patterns and body mass index
status in pregnancy: An assessment among
women reporting for antenatal care at the
Korle-Bu Teaching hospital, Ghana
Mary Amoakoh-Coleman1,2,3☯, Deda Ogum-Alangea4‡, Emefa Modey-Amoah4‡, Michael
Yao Ntumy5‡, Richard M. Adanu4‡, Samuel A. Oppong5☯*
1 Department of Epidemiology, Noguchi Memorial Institute for Medical Research, University of Ghana,
Legon, Ghana, 2 Department of Epidemiology and Disease Control, School of Public Health, University of
a1111111111
Ghana, Legon, Ghana, 3 Julius Global Health, Julius Center for Health Sciences and Primary Care,
a1111111111 University Medical Centre, Utrecht, The Netherlands, 4 Department of Population, Family and Reproductive
a1111111111 Health, School of Public Health, University of Ghana, Legon, Ghana, 5 Department of Obstetrics and
a1111111111 Gynecology, School of Medicine and Dentistry, University of Ghana, Accra, Ghana
a1111111111
☯ These authors contributed equally to this work.
‡ These authors also contributed equally to this work.
* wak72@yahoo.com
OPENACCESS
Abstract
Citation: Amoakoh-Coleman M, Ogum-Alangea D,
Modey-Amoah E, Ntumy MY, Adanu RM, Oppong
SA (2017) Blood pressure patterns and body mass Background
index status in pregnancy: An assessment among Maternal obesity in pregnancy has been linked with increased risk of pregnancy induced
women reporting for antenatal care at the Korle-Bu
hypertension (PIH). In some tertiary referral hospitals in Ghana, PIH is the leading cause of
Teaching hospital, Ghana. PLoS ONE 12(12):
e0188671. https://doi.org/10.1371/journal. institutional maternal mortality.
pone.0188671
Editor: Maria Cristina Vinci, Centro Cardiologico Objective
Monzino, ITALY
To evaluate blood pressure changes during pregnancy amongst different body mass index
Received: June 9, 2017 (BMI) groups and how this relates to the risk of developing PIH.
Accepted: November 10, 2017
Published: December 6, 2017 Methods
Copyright: © 2017 Amoakoh-Coleman et al. This is Women who had a dating ultrasound before 20 weeks gestation and registering for antena-
an open access article distributed under the terms tal care at the Korle-Bu Teaching Hospital in Accra, between February and December
of the Creative Commons Attribution License, 2013 and met the inclusion criteria were recruited into a cohort study. BMI was assessed at
which permits unrestricted use, distribution, and
baseline. Blood pressure measurements were taken at (±2) 24, 28 and 36 weeks. Primary
reproduction in any medium, provided the original
author and source are credited. outcome measure of interest during follow-up was a diagnosis of PIH at these points. BP
changes during follow up at the three points were measured. Descriptive analysis of base-
Data Availability Statement: All relevant data are
within the paper and its supportorting Information line factors was carried out and compared for the BMI groups. Relative risk (RR) of PIH was
files. estimated at 95% confidence interval.
Funding: The study was funded by the Fogarty
International Centre, Chronic Diseases (NCD- Results
LIFESPAN) Programme, through the
Cardiovascular Research Training (CaRT) Institute, Mean (SD) age for the 361 women was 30.9 (4.8) years. Incidence of PIH amongst the co-
Accra, Ghana. The funder have no role in data hort was 10.5% (95% CI: 7.45% - 14.45%) and 40.4% and 33.0% of them were overweight
PLOS ONE | https://doi.org/10.1371/journal.pone.0188671 December 6, 2017 1 / 13
Blood pressure patterns and body mass index in pregnancy
collection, analysis of results, data interpretation and obese respectively at baseline. Pregnant women who were obese at baseline had a
and the final decision to submit this manuscript. three-fold increased risk of PIH compared to those with normal BMI [RR = 3.01 (1.06–8.52),
Competing interests: The authors have declared p = 0.04].
that no competing interests exist.
Conclusion
Obese women have a significantly increased risk of PIH. Women should be screened at
booking for obesity status. Antenatal protocols should have interventions for prevention or
early detection of obesity and management of obesity to improve outcomes.
Introduction
The global epidemic of non-communicable disease (NCDs) has been linked to obesity, with a
highest prevalence in high income countries[1–3]. Obesity has been shown not only to be
prevalent in high-income countries but also display rising prevalence in low and middle-
income countries (LMIC)[4]. A survey of seven Sub Saharan African countries shows that obe-
sity prevalence increased by an average of 35% in the last two decades with some estimates
reaching as high as 50% [5]. Other studies estimate a doubling of obesity prevalence in the last
15 years, in West Africa, especially amongst women[4]
Studies in Ghana indicate that obesity prevalence among Ghanaian women ranges between
7.4–50%[6–11]. The obesity epidemic in Ghana is most notable among women in the repro-
ductive age group. Data from the 2008 Ghana Demographic and Health Survey (GDHS) sug-
gests that 29% of pregnant women are overweight and 12% are obese[11]. Two hospital-based,
surveys conducted in Ghana and Nigeria reported the prevalence of obesity in pregnancy to be
17.9% and 6.0% respectively[12,13].
Maternal obesity and excessive weight gain in pregnancy have been linked with increased
risk of pregnancy induced hypertension and consequently maternal and perinatal morbidity
and mortality[13–15]. Globally, hypertensive disease in pregnancy is the second direct cause of
maternal mortality[16]. It contributes 19–40% of maternal morbidity and deaths in Ghana,
second only to hemorrhage[17,18]. Recent reports from some tertiary referral hospitals in
Ghana indicate that hypertensive disease in pregnancy is now the leading cause of institutional
maternal mortality[19,20].
To date, interventions to control obesity and excessive weight gain during pregnancy have
not been implemented in Ghana. Although guidelines and protocols recognize hypertension
and diabetes, among others as independent risk factors for adverse outcome during pregnancy,
they are limited in their focus on the effect of obesity during pregnancy. Risk of obesity associ-
ated PIH has not been determined. Our aim was to evaluate blood pressure changes during
pregnancy amongst different body mass index (BMI) groups and how this relates to the risk of
developing PIH.
Materials and methods
A cohort study of pregnant women registering for antenatal care at the Korle-Bu Teaching
hospital, in Accra was conducted.
Accra was chosen because of its relatively high prevalence of obesity among women of
reproductive age and high antenatal coverage and skilled birth attendants rates[21,22]. The
Korle-Bu Teaching hospital is a referral hospital and registers about 1000 new antenatal atten-
dants every month with about 11,000 deliveries each year (figure from 2011 hospital report);
PLOS ONE | https://doi.org/10.1371/journal.pone.0188671 December 6, 2017 2 / 13
Blood pressure patterns and body mass index in pregnancy
which makes it an ideal site for this study. At each antenatal visit, weight, height and blood
pressure measurements are taken amongst others. Urine dipstick test for glucose and protein
are routinely done for all clients.
The sample size was computed using a risk ratio of 14% vs. 6% for hypertension in preg-
nancy, in the obese and the non-obese (underweight, normal and overweight) group respec-
tively. To detect a statistical difference, at a power of 80% and a 95% confidence interval, a
sample of 230 women was required for each group. An attrition rate of 20% was assumed
based on estimates of 15–20% for longitudinal studies. Total sample size required in each
group was 300 women, totaling 600.
All pregnant women 18 years and above attending antenatal care at the Korle-Bu Teaching
Hospital between the three months recruitment period with singleton pregnancy at 20 to 24
weeks gestation were identified and screened to ensure they meet the study criteria. Women
sampled were categorized into four groups according to their body mass index.
Inclusion Criteria: Women who had a dating ultrasound before 20 weeks gestation.
Women were excluded from the study if they registered after 24 weeks, had multiple preg-
nancy, had booking blood pressure of 140/90 mmHg or higher or on antihypertensive medica-
tion or was a known diabetic. Clients with chronic medical illness such as sickle cell disease,
HIV, severe anaemia, or severely underweight or any deformity that interfered with weight
and height measurements, were also excluded.
All first time antenatal clients were approached and screened with our screening tool. An
approved written consent form was administered to those who qualified based on our inclu-
sion and exclusion criteria. The women were weighed wearing only light clothing using recali-
brated weighing scale (HealthCare). Blood pressure was measured after clients have been
made to rest for 30 minutes and measurement taken from the right arm in the sitting position
using a standard adult size arm cuff sphygmomanometer (M2 Basic, OMRON IntelliTM
sense). Participant’s height was measured using a stadiometer without wearing any footwear
((HealthCare). Weight and height were measured twice and the average recorded. Pregnancy
was dated using combination of last menstrual period (LMP) and ultrasound performed before
twenty weeks. Where the LMP cannot be reliably recalled, a first trimester dating ultrasound
was used. A structured questionnaire was used to collect baseline data on socio-demographic
information, relevant medical history, past and current obstetric history, contraceptive and
drug history. The gestational age at booking, maternal weight, height and blood pressure mea-
surements at booking visit were also recorded. Folders of the recruited participants were
tagged to indicate participation in the study. Folder tags included a data entry sheet for records
such as delivery information and post-delivery outcomes (i.e. gestational age at delivery; type
of delivery; birth weight; maternal complications like eclampsia, postpartum hemorrhage; pre-
sentation of baby at birth and NICU admission).
All participants were managed by the usual antenatal care protocol at the Korle-Bu Teach-
ing hospital. In addition all participants had BP measurements taken at (+/-2) 24, 28 and 36
weeks as described above. Other measures of antenatal care were taken and at delivery a final
set of outcome data were collected.
Primary outcome measure of interest during follow-up was a diagnosis of gestational
hypertension or pregnancy induced hypertension (PIH) at or around (+/- 2) 24, 28 and 36
weeks of gestation. Secondary outcome measures of interest during follow-up were mean sys-
tolic and diastolic BP changes during follow up at or around (+/- 2) weeks 24, 28 and 36
weeks.
The diagnosis of gestational hypertension for clients in the study was defined as any de
novo record of systolic BP of at least 140 mmHg and/or a diastolic BP of at least 90 mmHg
after 20 weeks of gestation. Measurements were taken at 24, 28 and 36 weeks of gestation.
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Blood pressure patterns and body mass index in pregnancy
Data was entered into SPSS version 16. Descriptive analysis of women at baseline was car-
ried out and compared for the BMI groups. Continuous variables such as weight, height and
blood pressure measurements were compared using the student’s t-test while Chi-Square tests
were used to determine associations between categorical variables.
Mean BP changes for the BMI groups were depicted in graphs. Linear regression was used
to assess relationships between the outcome and maternal BMI at first visit and BP changes
during the pregnancy at 24, 28 and 36 weeks of gestation. Risk for PIH amongst different BMI
categories was assessed using logistic regression. Statistical significance was determined at
p<0.05 at the 95% confidence level.
Ethical approval
Ethical approval was obtained from the Ethical Review Board of the Noguchi Memorial Insti-
tute for Medical Research, University of Ghana, Legon (Protocol number NMIMR-IRB 042/
12-13) before data collection commenced. Permission was also obtained from the Korle-bu
Teaching Hospital before any contact was made with participants. A written informed consent
was obtained from each participant recruited.
Results
Baseline characteristics
A total of 629 women were recruited from March 2013 –December 2013 but only 508 women
completed the study. This gave us a loss to follow-up rate of 19.2%. For the 508 who completed
the study, the outcome measure of PIH diagnosis was obtained for 361 women, translating to
missing data of 28.9%. We did a complete case analysis for the 361 women, as the baseline
characteristics, including BMI status, of those without data on the outcome were similar to
that of those with data. Also because data on outcome for the obese was less compared to the
non-obese groups, we decided to do analysis for each of the BMI groups instead of the origi-
nally intended obese and non-obese categorization. "Fig 1" is the representation of participants
flow through the study.
The mean (SD) age of the women was 30.9 (4.8) years, weight was 73.2 (14.5) kg; height of
160.6 (5.8) cm and gestational age of 20.5 (1.9) weeks with hemoglobin of 11.1 (1.2) g/dl at
baseline. A total of 65.4% of them had secondary or higher education with 2.8% having no edu-
cation. Most of them were employed (90.9%), married (90.0%) and Christians (87.8%). Also at
baseline, 25.8% had normal BMI, 40.4% were overweight and 33.0% were obese. Underweight
women were only 3 (0.8%). The overweight and obese women were significantly older, multip-
arous, Christian, and had higher baseline SBP and DBP. Variations in BMI were mainly due to
differences in weight, with mean weight (SD) of normal, overweight and obese being 58.8 (6.2)
kg, 69.8 (6.4) kg and 88.8 (11.6) kg respectively (p<0.01). They however did not differ from
the normal BMI group with respect to education, employment and residence. The mean (SD)
systolic BP and diastolic BPs for participants were 111.0 (11.1) mmHg and 68.9 (9.3) mmHg
respectively. A total of 22 (6.10%) of participants had systolic blood pressure of 130 mmHg or
more, with majority of these being obese (63.60%). The baseline BPs of the groups was signifi-
cantly different. The mean systolic BP of the obese was 113.00 mmHg compared to that of the
normal BMI group of 108.2 mmHg (p = 0.03) while mean diastolic BP of the obese was 71.2
mmHg compared to 66.5 mmHg for the normal BMI women (p<0.01). More obese (11.8%)
and overweight (4.8) women had higher systolic BPs compared to normal BMI women
(p = 0.01) at baseline. Table 1 describes the baseline characteristics of the women.
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Blood pressure patterns and body mass index in pregnancy
Fig 1. Flow chart of participants in the study.
https://doi.org/10.1371/journal.pone.0188671.g001
Risk of PIH and associated factors
Overall, the incidence of PIH amongst our cohort was 10.5% (95% CI: 7.45% - 14.45%). Major-
ity of these were overweight (40.4%) and obese (33.0%) at baseline. Risks of systolic and dia-
stolic PIH at 36 weeks were 4.2% and 2.8% respectively. Risks of PIH (either systolic or
diastolic) at 24, 28 and 36 weeks were 1.7%, 5.3% and 5.8% respectively. Risk of pre-eclampsia
and eclampsia was 3.9%. There were no significant differences between the groups that were
diagnosed with PIH and those who were not with respect to age, parity, height and gestational
age at booking. There were no significant differences between the two groups at baseline with
respect to socioeconomic characteristics. There were more obese women at baseline who
developed PIH (44.7%) compared to overweight women (34.2%). Consequently, there were
fewer obese women (31.6%) than overweight women (41.2) at baseline who did not develop
PIH during follow-up. Table 2 describes the characteristics of the women with and without
PIH.
There was significant difference in mean baseline hemoglobin of women diagnosed with
PIH compared to those without PIH (11.6g/dl vs 11.0g/dl, p = 0.02). Women diagnosed with
PIH recorded significantly higher mean systolic and diastolic BP at baseline compared to their
non-PIH counterparts (119.7/76.8 mmHg vs 110.0/68.0 mmHg, p<0.01).
There is a significantly higher risk of PIH in obese women compared to women with nor-
mal BMI [RR 3.01 (1.06–8.52), p = 0.04]. However, the elevated risk of PIH among overweight
compared to women of normal weight was not statistically significant [RR 1.54 (0.55–4.35),
p = 0.41]. Although only 9 (40.90%) of those with baseline systolic BP higher than 130 mmHg
developed PIH, the crude relative risk of developing PIH if baseline systolic BP is higher than
130 mmHg was crude RR 7.40 [(2.92–18.78), p<0.001]. When adjusted for socioeconomic fac-
tors as well as BMI category, baseline systolic BP higher than 130mmHg was still associated
with increased risk of developing PIH over six-fold [adjusted RR 6.59 (2.33–18.67), p<0.001),
Table 3.
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Blood pressure patterns and body mass index in pregnancy
Blood pressure changes during follow up
Blood pressures (systolic and diastolic) during follow-up at weeks 24, 28 and 36 were com-
pared with baseline blood pressure for participants and the mean changes during follow-up
estimated for normal, overweight and obese women. Underweight women were excluded in
this analysis because of their small number (3). For women with normal BMI, mean systolic
blood pressure changes at the 3 points were 4.11, 4.00 and 6.70 mmHg respectively while
mean diastolic blood pressure changes were -0.28, 0.42 and 2.40 mmHg respectively. For obese
women however, mean systolic blood pressure changes at the 3 points were 1.93, 3.03 and 4.78
Table 1. Baseline characteristics of participants and comparison among different BMI groups.
Variable All Participants Underweight Normal Overweight Obese p-value
Frequency N (%) / Mean (SD)
BMI
Underweight 3 (0.8)
Normal 93 (25.8)
Overweight
Obese 146 (40.4)
119 (33.0)
Education
None 10 (2.8) 0 (0.0) 2 (3.6) 4 (2.7) 4 (3.4)
Primary 115 (31.9) 1 (33.3) 23 (41.8) 52 (35.6) 39 (32.8)
Secondary
Tertiary 91 (25.2) 2 (66.7) 30 (54.5) 38 (26.0) 21 (17.6)
145 (40.2) 0 (0.0) 0 (0.0) 52 (35.6) 55 (46.2)
Employed
No 32 (8.9) 0 (0.0) 11 (11.8) 14 (9.6) 7 (5.9)
Yes 328 (90.9) 3 (100.0) 82 (88.2) 132 (90.4) 112 (94.1)
Religion
Christian 317 (87.8) 1 (33.3) 79 (84.9) 128 (88.9) 109 (92.4)
Muslim 41 (11.4) 2 (66.7) 14 (15.1) 16 (11.1) 9 (7.6)
Other
3 (0.8)
Marital status
Single 22 (6.1) 0 (0.0) 6 (6.5) 10 (6.8) 6 (5.0)
Married 325 (90.0) 3 (100.0) 84 (90.3) 130 (89.0) 108 (90.8)
Cohabiting
3 (0.8) 0 (0.0) 3 (3.2) 6 (4.1) 5 (4.2)
Ethnicity
Akan 211 (58.4) 3 (100.0) 57 (62.0) 86 (58.9) 65 (55.1)
Ga/ Dangme 84 (23.3) 0 (0.0) 15 (16.3) 23 (15.8) 14 (11.9)
Ewe
Northern 52 (14.4) 0 (0.0) 16 (17.4) 32 (21.9) 36 (30.5)
12 (3.3) 0 (0.0) 4 (4.3) 5 (3.4) 3 (2.5) 0.63
Residence
Rural 11 (3.0) 0 (0.0) 4 (4.3) 2 (1.4) 5 (4.2)
Urban 349 (96.8) 3 (100.0) 88 (95.7) 144 (98.7) 113 (95.8)
Age (years) 30.90 (4.81) 27.67 (2.52) 29.56 (5.05) 30.80 (4.70) 32.16 (4.49) <0.01
Parity 1.11 (1.10) 1.00 (1.00) 0.68 (0.93) 1.10 (1.12) 1.46 (1.14) <0.01
Weight (kg) 73.16 (14.54) 46.67 (6.66) 58.79 (6.19) 69.78 (6.38) 88.84 (11.62) <0.01
Height (cm) 160.60 (5.78) 161.33 (8.500 160.87 (5.93) 159.81 (5.58) 160.65 (5.83) 0.15
Gestational age at booking (wks) 20.46 (1.85) 22.67 (1.16) 20.47 (1.84) 20.52 (1.76) 20.46 (1.92) 0.17
Baseline systolic BP (mmHg) 110.99 (11.13) 109.00 (11.35) 108.19 (10.35) 111.49 (10.54) 112.99 (12.09) 0.03
Baseline diastolic BP (mmHg) 68.87 (9.31) 59.33 (2.08) 66.47 (9.49) 68.73 (8.42) 71.16 (9.75) <0.01
Baseline systolic BP > 130mmHg 22 (6.10) 0 (0.00) 1 (4.50) 7 (31.80) 14 (63.60) 0.01
Hemoglobin (g/dl) 11.07 (1.22) 11.03 (0.25) 11.11 (1.13) 11.1 (1.13) 11.00 (1.29) 0.94
https://doi.org/10.1371/journal.pone.0188671.t001
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Blood pressure patterns and body mass index in pregnancy
Table 2. Association of baseline characteristics with diagnosis of PIH among cohort.
Variable PIH No PIH Yes p-value
Incidence 323 (89.5) 38 (10.5)
BMI
Underweight 2 (0.6) 1 (33.3) 0.19
Normal 86 (26.6) 7 (18.4)
Overweight 133 (41.2) 13 (34.2)
Obese 102 (31.6) 17 (44.7)
Education 0.34
None 10 (3.1) 0 (0.0)
Primary 99 (30.7) 16 (42.1)
Secondary 81 (25.1) 10 (26.3)
Tertiary 133 (41.2) 12 (31.6)
Employed 0.33
No 27 (8.4) 5 (13.2)
Yes 295 (91.6) 33 (86.8)
Religion 0.73
Christian 284 (88.2) 33 (86.8)
Muslim 36 (11.8) 5 (13.2)
Marital status 0.11
Single 22 (6.8) 0 (0.0)
Married 290 (89.5) 35 (92.1)
Cohabiting 11 (3.4) 3 (7.9)
Ethnicity 0.87
Akan 189 (58.7) 22 (57.9)
Ga/ Dangme 77 (23.9) 7 (18.4)
Ewe 46 (14.3) 6 (15.8)
Northern 10 (3.1) 2 (5.3)
Residence 0.95
Rural 10 (3.1) 1 (2.6)
Urban 312 (96.9) 37 (97.4)
Age (years) 30.87 (4.78) 31.16 (5.16) 0.73
Parity 1.11 (1.09) 1.05 (1.18) 0.74
Weight (kg) 72.66 (14.29) 77.39 (10.08) 0.05
Height (cm) 160.56 (5.75) 160.97 (5.91) 0.68
Gestational age at booking (wks) 20.49 (1.70) 20.18 (2.85) 0.34
Baseline systolic BP (mmHg) 109.97 (10.62) 119.68 (11.66) <0.01
Baseline diastolic BP (mmHg) 67.95 (8.63) 76.76 (11.18) <0.01
Baseline systolic BP > 130 (mmHg) Yes 13 (4.00) 9 (23. 70) <0.01
Hemoglobin (g/dl) 11.01 (1.21) 11.59 (11.18) 0.02
https://doi.org/10.1371/journal.pone.0188671.t002
mmHg respectively while mean diastolic blood pressure changes were -0.45, -0.40 and 1.27
mmHg respectively. The differences in the mean blood pressure were however not significant
("Figs 2 and 3"). There were however significant differences in mean pressure changes between
those who developed PIH and those who did not at the three points (Table 4).
Discussion
We found overweight and obese pregnant women in our sample to be younger and multipa-
rous. Other studies have found that women with higher BMI tend to be multiparous, just as we
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Blood pressure patterns and body mass index in pregnancy
found, but older[23,24]. This could be due to the fact that percentage body fat increases with
age[25]. The absence of a significant association between socioeconomic factors such as educa-
tion and employment and BMI is rather contrary to what other studies have found [26–28]
While in the past obese women tended to have lower educational and economic status in
higher income countries with the reverse relationship for lower to middle income countries,
recent studies show different relationships between obesity and specific socio-economic fac-
tors for different populations[29–32].
This study also found significant variations in baseline systolic and diastolic BPs for the
three BMI categories, with obese and overweight women having higher BPs compared to
women with normal BMI. Several studies have also found that increasing BMI is associated
with increasing BPs and increased risk or odds of PIH and its complications[23,24,32]. Most
of the studies however used pre-pregnancy weights to estimate BMI, while we used weight at
20 weeks of gestation. It is important that women are educated to know their weights, espe-
cially pre-pregnancy. This will be facilitated if pre-pregnancy services are provided by the
health system, and also utilized by women before they get pregnant. This will also be an avenue
to encourage women to keep a healthy weight or reduce excess weight where necessary before
pregnancy, despite recent literature that suggests such gains with respect to reduction in com-
plications of PIH would be minimal[33].
Incidence of PIH amongst our cohort of women was 10.5%, with 44.4% and 33.0% of these
women being overweight and obese women respectively. The risk of PIH increased from 24
weeks to 36 weeks of gestation. The PIH incidence of 10.5% was high compared to some other
studies[34] but lower compared to that found in other parts of Africa[35,36] and in an Austra-
lian nulliparous cohort (12.6%)[26]. Nulliparity has also been associated with increased risk of
PIH and this has been a consistent finding as shown in a systematic review[27], but we did not
find that in our study. It is not clear to us how the relationship between obesity and multi-par-
ity seen in our study contributes to this finding. Although we excluded women with chronic
Table 3. Risk of PIH among the BMI groups.
Body Mass Index category RR 95% CI p-value
Crude
Underweight 6.14 0.49–76.43 0.16
Normal - - -
Overweight 1.20 0.46–3.13 0.71
Obese 2.05 0.81–5.17 0.13
Adjusted for baseline characteristics*
Underweight 20.27 0.98–418.41 0.05
Normal - - -
Overweight 1.54 0.55–4.35 0.41
Obese 3.01 1.06–8.52 0.04
Adjusted for baseline characteristics and GDM at 28 weeks
Underweight 6.28 0.29–137.10 0.24
Normal - - -
Overweight 1.28 0.41–3.96 0.67
Obese 2.72 0.85–8.76 0.09
Risk of PIH amongst those with baseline systolic BP higher than 130 mmHg**
6.59 2.33–18.67 <0.001
* These are age, parity, religion, ethnicity, gestational age at booking, and baseline systolic and diastolic
blood pressures
** Adjusted for baseline factors and baseline BMI category
https://doi.org/10.1371/journal.pone.0188671.t003
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Blood pressure patterns and body mass index in pregnancy
Fig 2. Mean systolic blood pressure changes for BMI groups of participants during follow up.
https://doi.org/10.1371/journal.pone.0188671.g002
hypertension at baseline, we found that women with higher baseline BPs still had an increased
risk of PIH, which is also in agreement with existing literature[27,33].
During follow up, there were significant differences between the mean BP changes at gesta-
tional weeks 24, 28 and 36 compared to baseline, between women who had a diagnosis of PIH
and those who did not. There were however no such significant differences between follow-up
mean BP changes for the different BMI groups.
A key limitation of this study is the fact that weights used for estimating the BMI were not pre-
pregnancy weights. The baseline weights were around 20 weeks and thus some substantial preg-
nancy weight gain may have taken place, affecting the BMI groups and thus the risk categoriza-
tion. This limitation occurred mainly because in Ghana most women do not know their pre-
pregnancy weights, and no previous studies have estimated how much weight women in this
setting are likely to gain by gestational age 20 weeks that can be used in adjusting weights in our
analysis. Coupled with this limitation was the fact that we excluded women who were already
hypertensive at baseline from the study. Also, follow-up BP measurements were missing for a
good number of participants (range 108–132 at the 3 follow-up points) who nevertheless com-
pleted the study upon delivery. Most of these participants were in the obese group. This limits our
sample for analysis and thus it is possible that there may be underestimation of the risk of PIH
amongst our study population. The strength of our study is the fact we used standard BP measure-
ment tool and PIH definition and thus our findings are comparable to studies in other settings.
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Blood pressure patterns and body mass index in pregnancy
Fig 3. Mean diastolic blood pressure changes for BMI groups of participants during follow up.
https://doi.org/10.1371/journal.pone.0188671.g003
Conclusion
The incidence of PIH among our cohort was 10.5% and obese women have a three-fold
increased risk of PIH. Pregnant women with systolic BP of greater than 130mmHg after 20
weeks have a high risk of developing PIH. Women should be screened at booking for obesity
Table 4. Mean blood pressure changes from baseline during follow up among the PIH groups.
Diagnosis of PIH 24 weeks 28 weeks 36 weeks
Systolic blood pressure changes: Mean (SD) mmHg
All women 1.77 (11.88) 3.13 (12.75) 5.89 (13.66)
No PIH 1.08 (11.74) 2.47 (11.86) 4.73 (12.62)
PIH 8.87 (11.21) 10.47 (17.28) 16.36 (17.89)
p-value <0.01 <0.01 <0.01
Diastolic blood pressure changes (Mean (SD)mmHg)
All women -0.29 (9.51) -0.39 (10.33) 2.22 (10.37)
No PIH -0.54 (9.50) -0.35 (9.87) 1.64 (9.56)
PIH 2.37 (9.35) 6.89 (12.03) 7.47 (15.13)
p-value 0.11 <0.01 <0.01
https://doi.org/10.1371/journal.pone.0188671.t004
PLOS ONE | https://doi.org/10.1371/journal.pone.0188671 December 6, 2017 10 / 13
Blood pressure patterns and body mass index in pregnancy
status. Antenatal protocols should have interventions for prevention or early detection and
management of obesity in pregnancy to improve outcomes.
Supporting information
S1 File.
(XLS)
Author Contributions
Conceptualization: Mary Amoakoh-Coleman, Deda Ogum-Alangea, Emefa Modey-Amoah,
Michael Yao Ntumy, Richard M. Adanu, Samuel A. Oppong.
Data curation: Mary Amoakoh-Coleman, Deda Ogum-Alangea, Emefa Modey-Amoah,
Michael Yao Ntumy, Samuel A. Oppong.
Formal analysis: Mary Amoakoh-Coleman, Samuel A. Oppong.
Funding acquisition: Mary Amoakoh-Coleman, Richard M. Adanu, Samuel A. Oppong.
Investigation: Mary Amoakoh-Coleman, Deda Ogum-Alangea, Emefa Modey-Amoah,
Michael Yao Ntumy, Samuel A. Oppong.
Methodology: Mary Amoakoh-Coleman, Deda Ogum-Alangea, Emefa Modey-Amoah,
Michael Yao Ntumy, Samuel A. Oppong.
Project administration: Samuel A. Oppong.
Supervision: Richard M. Adanu, Samuel A. Oppong.
Validation: Mary Amoakoh-Coleman, Deda Ogum-Alangea.
Writing – original draft: Mary Amoakoh-Coleman, Samuel A. Oppong.
Writing – review & editing: Mary Amoakoh-Coleman, Deda Ogum-Alangea, Emefa Modey-
Amoah, Michael Yao Ntumy, Richard M. Adanu, Samuel A. Oppong.
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