Results
There were 9420 White British and South Asian women who had a BMI
between 11 and 80 kg/m2. Following exclusions for
missing GHQ data (n=1596, 17%), a total sample size of 7824 women was
available for analysis. The final sample included 3514 White British and
4310 South Asian women (3780 Pakistani, 343 Indian and 187 Bangladeshi).
There was no statistically significant difference between the included
and excluded group in terms of age (27.3 ± 0.1 versus 27.3 ± 0.14) or
deprivation level (Low deprivation 34.5% vs 31.3%, high deprivation
65.5% vs 68.7%) (Table S2) . However, the included population
had significantly higher education levels than those excluded
(>A-level 24.6% vs 21.1%, A-level 15.8% vs 8.9%,
p<0.0001) and were more likely to smoke (17.6% vs 10.2%,
p<0.0001) (Table S2) .
Table 1 shows the summary of characteristics of the included
sample of pregnant women, stratified by ethnicity, with tests for
association between the ethnic groups. In the included population, South
Asian women were significantly older than White British women, had a
higher percentage with >A-level education level, were more
likely to live in the highest deprivation areas, less likely to smoke,
had a higher proportion with depression, but a lower proportion with
anxiety, independent of early pregnancy BMI. There was a significant
association between BMI and ethnicity, with a higher proportion of South
Asian than White British women in the overweight and obese categories(Table 1) .
Within the White British ethnic group, women with obesity were
significantly older, had a lower percentage with >A-level
education level, were more deprived and less likely to smoke, compared
to women with a recommended BMI (Table 2) . Overall, 36% of
White British women had depression and 48% had anxiety. Within South
Asian women, those with obesity were significantly older and had a lower
percentage with >A-level education level compared with
women with a recommended BMI. There was no significant association
between deprivation level, smoking status, depression or anxiety and
early pregnancy BMI among South Asian women. In both the South Asian and
White British groups, women with an obese BMI had higher proportions
with depression and anxiety, compared with women with a recommended BMI,
although this was not statistically significant.
There was no significant association between depression and early
pregnancy BMI among White British women (Table 3) . Univariate
regression found that South Asian women with an overweight BMI had
significantly higher odds of depression than South Asian women of
recommended BMI (odds ratio (OR) 1.17, 95% confidence interval (CI)
1.00-1.36). After adjusting for age, education level, smoking and
deprivation, the adjusted odds ratio (AOR) was no longer significant
(AOR 1.16, 95% CI 0.99-1.36). No other associations between BMI and
depression were found to be significant. Interaction analysis found no
significant association between ethnicity and antenatal depression
within any BMI category (Table 3).
Table 4 shows the crude and adjusted ORs for screening positive
for anxiety within each ethnic group for each BMI category and AORs for
interaction analysis between White British and South Asian women.
Univariate analysis showed that White British women with an overweight
BMI had significantly higher odds of anxiety compared with White British
women of recommended BMI (OR 1.21, 95% CI 1.03-1.42). This remained
significant after adjusting for age, ethnicity, education level, smoking
and deprivation (AOR 1.25, 95% CI 1.05-1.47). White British women with
obesity also had higher odds of anxiety compared with recommended weight
(OR 1.18, 95% CI 1.00-1.39). However, after adjustments this result was
no longer significant (AOR 1.13, 95% CI 0.95-1.35). There was no
significant association between anxiety and early pregnancy BMI among
South Asian women. Interaction analysis found no significant association
between ethnicity and antenatal anxiety within any BMI category(Table 4) .
Other exposure variables were shown to be associated with antenatal
depression and anxiety within White British and South Asian women(Table S3). For White British women, maternal age (AOR 0.98,
95% CI 0.97-0.99) and education (no education AOR 2.12, 95% CI
1.63-2.76) were significantly associated with depression, and smoking
was significantly associated with both depression (AOR 1.32, 95% CI
1.12-1.56) and anxiety (AOR 1.34, 95% CI 1.14-1.57). For South Asian
women, maternal age (AOR 1.02, 95% CI 1.01-1.04) and education (no
education AOR 0.65, 95% CI 0.55-0.78) were significantly associated
with anxiety, and smoking was significantly associated with both
depression (AOR 2.08, 95% CI 1.49-2.91) and anxiety (AOR 2.87, 95% CI
2.02-4.07).