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Maternal and Child Health Journal ISSN 1092-7875 Matern Child Health JDOI 10.1007/s10995-012-1108-6

Smoking Status and Factors Associatedwith Smoking of First-Time MothersDuring Pregnancy and Postpartum:Findings from the Healthy Beginnings Trial

Huilan Xu, Li Ming Wen, Chris Rissel &Louise A. Baur

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Smoking Status and Factors Associated with Smokingof First-Time Mothers During Pregnancy and Postpartum:Findings from the Healthy Beginnings Trial

Huilan Xu • Li Ming Wen • Chris Rissel •

Louise A. Baur

� Springer Science+Business Media, LLC 2012

Abstract This study aimed to investigate smoking status

and factors associated with smoking among first-time

mothers and their partners during pregnancy and post-

partum. A prospective cohort study with 201 first-time

mothers was conducted using data from the Healthy

Beginnings Trial, undertaken in one of the most socially

and economically disadvantaged areas of south-western

Sydney, Australia in 2007–2010. Smoking status of the

mothers and their partner and smoke-free home status were

assessed at 30–36 weeks of pregnancy, and also at 6, 12

and 24 months postpartum. Multivariable two-level logis-

tic random-intercept models were conducted. Smoking

rates of the first-time mothers were 17.6 % during preg-

nancy and 22.5 % postpartum. The likelihood of being a

current smoker among the mothers significantly increased

after giving birth, with an adjusted odds ratio of 3.96 (95 %

CI 1.3–12.1) at 6 months, 6.19 (95 % CI 1.84–30.9) at

12 months, and 6.58 (95 % CI 1.86–23.23) at 24 months

postpartum. Mothers’ smoking status was significantly

inversely associated with educational level and positively

associated with their partner’s smoking status. In addition,

mothers who breastfed their child were significantly less

likely to be a smoker, with an adjusted odds ratio of 0.10

(95 % CI 0.02–0.68). Although pregnancy may act as a

motivator to quit smoking, it is of concern that maternal

smoking rate increased after giving birth. Smoking cessa-

tion programs should not only focus on smoking in preg-

nancy, but also address other risk factors, particularly in

postpartum women and their partners.

Keywords Smoking status � First-time mothers �Pregnancy and postpartum

Introduction

Pregnancy and childbirth are recognized as good opportu-

nities for parents to quit smoking and institute a smoke-free

home [1]. Unfortunately, pregnancy related smoking

abstinence does not typically lead to lifelong abstinence,

even with a smoking cessation intervention [2, 3]. Previous

studies have found that many mothers who quit during

pregnancy relapse within 6 months postpartum [4–8]. For

example, one study found that 41 % of those mothers who

quit smoking during pregnancy resumed smoking at

2 weeks postpartum [8]. Another study found that 72 % of

those mothers returned to smoking at 12–22 months [9].

Some factors such as mother’s educational level, having a

partner who was a smoker, and self-reported stress were

identified as contributing factors to smoking relapse [4–10].

Converting smoking abstinence during pregnancy to

lifelong abstinence is beneficial not only to the health of

mothers but also to the health of children and other family

members. Many studies have found that smoking abstinence

after giving birth is associated with longer breastfeeding time

[11–17]. Hence, young children benefit from their mother’s

smoking abstinence by both being not exposed to environ-

mental tobacco smoke and longer breastfeeding. Mothers’

H. Xu � L. M. Wen (&)

Health Promotion Service, South Western Sydney and Sydney

Local Health Districts, Level 9, King George V Building,

Missenden Road, Camperdown, NSW 2050, Australia

e-mail: lmwen@email.cs.nsw.gov.au

L. M. Wen � C. Rissel � L. A. Baur

School of Public Health, Sydney Medical School,

University of Sydney, Sydney, NSW 2050, Australia

L. A. Baur

Discipline of Paediatrics and Child Health, Sydney Medical

School, University of Sydney, Sydney, NSW 2050, Australia

123

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DOI 10.1007/s10995-012-1108-6

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smoking abstinence is also beneficial to their next pregnancy

[18]. Their partner may also be persuaded to quit smoking or

at least declare their home smoke-free [19]. Therefore,

understanding the factors associated with the smoking status

of mothers and their partners during pregnancy and the

postpartum period may help to develop effective interven-

tion strategies regarding parent smoking cessation.

Most previous studies on maternal smoking have

\1 year follow-up, or only have examined smoking rates

and risk factors using cross-sectional data [5, 6, 8–11, 13–

16, 20]. However, some factors of interest might change

over time for each individual, such as smoking status,

marital status, household income, and stress level.

To investigate smoking status and the factors associated

with smoking among first-time mothers and their partners,

as well as smoke-free home status during pregnancy and

postpartum, we conducted a longitudinal data analysis

using prospective cohort data derived from the Healthy

Beginnings Trial which followed mothers from 30 to

36 weeks of pregnancy to 24 months postpartum [21].

Methods

Study Design

A prospective cohort study was conducted using data from

the Healthy Beginnings Trial, which was undertaken in one

of the most socially and economically disadvantaged areas

of south-western Sydney in 2007–2010. The study was

approved by the Ethics Review Committee of Sydney

South West Area Health Service (RPAH Zone). The details

of the Healthy Beginnings Trial research protocol have

been reported elsewhere [21].

Sample Selection

The Healthy Beginnings Trial is a home-based randomised

controlled trial aiming to determine whether a home-based

early intervention could be effective in improving infant

feeding practice and reducing overweight and obesity for

children at age 2 years. A total of 667 first-time mothers at

24–34 weeks of pregnancy were recruited to the trial from

antenatal clinics at Liverpool or Campbelltown Hospitals,

located in south-western Sydney, Australia. First-time

mothers who were aged 16 years and over, and able to

communicate in English were eligible for the trial. Once

eligibility was established and consent obtained, mothers

were asked to fill in a registration form with their contact

information to allow the research assistants to make further

arrangements for the baseline data collection.

For this particular study, we only selected mothers who

were allocated to the control group (n = 330) to avoid any

potential effects of the intervention (i.e. breastfeeding). In

the control group, 201 mothers were interviewed at their

home before giving birth. Another 129 mothers who were

interviewed within 1 month after giving birth were exclu-

ded, as we were not able to obtain late pregnancy smoking

information for these mothers.

Data Collection

Face-to-face interviews with each participating mother

were conducted by one of two research assistants at

30–36 weeks of pregnancy, and also at 12 and 24 months

postpartum, respectively. A telephone interview survey

with participating mothers was also conducted by a

research assistant at 6 months postpartum. The interviews

asked a range of questions including the mother’s demo-

graphic characteristics, general health status, smoking sta-

tus, smoke-free home status, breastfeeding, and their

partners’ smoking status. The majority of these questions

have been validated in an adult population and are widely

used in NSW population health surveys [22].

To assess the smoking status of mothers and their

partners, mothers were asked, ‘currently, are you a daily

smoker, or occasionally smoker, did you quit smoking

during pregnancy, did you quit smoking sometime ago, or

have you never smoked?’ The mothers were also asked to

report on their partner’s smoking status. For this analysis,

daily or occasional smokers were categorised as current

smokers and the rest were non-smokers.

To assess smoke-free home status, mothers were asked,

‘Which of the following best describes your home situation?’

It was categorised as a smoke-free home if mothers reported

no one smoked inside the home. To assess breastfeeding

status, mothers, at 6, 12, and 24 months postpartum, were

asked ‘Is your child currently being breastfed?’

Statistical Methods

Statistical analyses were carried out using Stata 10 [23].

The relationship of mothers’ smoking status at baseline

(late pregnancy) with demographic variables was examined

using Pearson Chi-square tests. In this study, we had lon-

gitudinal data with 4 measurement points (at late preg-

nancy, 6, 12, and 24 months postpartum), which can be

conceptualised as two-levels with the time points (level 1)

nested in subjects (level 2). Because the measures of a

particular outcome (i.e. smoking status) at 4 time points

from an individual are highly correlated, in the sense that

the measures from the same individual are likely to be

more similar than that from different individuals,

these correlations have to be taken into account when

building statistical models. To address these issues we

used univariable and multivariable two-level logistic

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random-intercept models to analyse how smoking status of

mothers and their partner, and smoke-free home status

changed over time (late pregnancy, 6, 12, and 24 months

postpartum) and what the contributing factors were. Odds

ratios (ORs), adjusted ORs (AOR) and 95 % confidence

intervals (CIs) were estimated.

Four multivariable two-level logistic random-intercept

models were fitted. A stepwise selection process was used

to build the final models. Subjects with missing data at all 4

time points for any variables in the two-level random-

intercept models were excluded from analysis [24, 25].

In the first model (the outcome was mothers’ smoking

status at late pregnancy, 6, 12, and 24 months postpartum),

the effect of time was adjusted for partner’s smoking status

that varied over this period of time, and mothers’ educa-

tional level at late pregnancy. In this model breastfeeding

was not included since there was no breastfeeding infor-

mation at late pregnancy.

The second multivariable two-level logistic random-

intercept model was fitted to investigate the effect of cur-

rent breastfeeding status (yes, no) on mothers’ postpartum

smoking status over time (6, 12, and 24 months post-

partum). The effect of breastfeeding was adjusted for

partner’s smoking status that varied over time and mother’s

education level.

In the third model (the outcome was the partner’s smoking

status at late pregnancy, 6, 12, and 24 months postpartum),

the effect of time was adjusted for mother’s smoking status

that varied over time, and partner’s educational level.

The fourth model was fitted to investigate how the

smoke-free home status changed during the period of late

pregnancy and 24 months postpartum. The effect of time

was adjusted for mothers’ employment status that varied

over this period of time and partner’s educational level.

Results

Of 201 mothers selected from the baseline (late pregnancy),

172, 162 and 146 remained in the study at 6, 12, and

24 months postpartum, respectively. The smoking rate of

mothers was 17.6 % at late pregnancy, and increased to 22, 25

and 21 % at 6, 12 and 24 months postpartum, respectively.

At late pregnancy, 12 % of the mothers were a ‘‘current

smoker’’, 26 % were former smokers and 62 % had never

smoked. Of those who never smoked, 1 % became a smoker

at 1 year and kept smoking at 2 years postpartum. Another

2 % mothers became a smoker for the first time at 2 years.

Of those who were former smokers in late pregnancy, 24 %

returned to smoking at 6 months postpartum and kept

smoking at 1 year postpartum. Another 9 % returned to

smoking at 1 year postpartum (33 % in total). At 2 years

postpartum 27 % kept smoking.

As shown in Table 1, mothers’ demographic character-

istics such as age, employment status, educational level and

country of birth were significantly associated with mother’s

smoking status at late pregnancy. The proportion of current

smokers was much higher in younger mothers (28 % for

16–24 years of age) than older mothers (10 % for over

25 years of age, P = 0.001). Mothers who were employed,

non-Australia born, or had a higher education level were

significantly less likely to be current smokers. Comparisons

of socio-demographics were made between those included

and excluded and no significant differences were found

between the groups.

Model 1

Compared with smoking status at late pregnancy, mothers’

likelihood of being a current smoker significantly increased

after giving birth, with an adjusted odds ratio of 3.96 (95 % CI

1.30–12.06) at 6 months, 6.19 (95 % CI 1.84–30.90) at

12 months and 6.58 (95 % CI 1.86–23.23) at 24 months

postpartum, after adjustment for partner’s smoking status, and

mothers’ education level (Table 2). However, these odds

ratios did not differ significantly (P = 0.62). Hence, mothers’

likelihood of being a current smoker significantly increased

after giving birth but did not change significantly over the 6, 12

and 24 months postpartum period. Mothers’ smoking status

was associated with their partner’s smoking status and

mothers’ educational level. Mothers with a partner being a

current smoker were more likely to be current smokers (AOR

13.01, 95 % CI 3.23–52.46) (Table 2). Compared with those

who only had school certificate or lower, mothers who com-

pleted secondary school or higher (AOR 0.007, 95 % CI

0.0006–0.08) were significantly less likely to be current

smokers. Mothers’ age, marital status and country of birth

were not significantly associated with mother’s smoking sta-

tus after adjustment for mother’s educational level.

Model 2

Table 3 shows factors associated with first-time mothers

being current smokers after giving birth using a multivariable

two-level logistic random-intercept model. Compared with

smoking status at 6 months postpartum, mothers’ likelihood

of being a current smoker increased at 12 and 24 months

postpartum with an odds ratio of 2.20 or 1.98, respectively, but

they were not statistically significant (trend test P = 0.35).

This result is consistent with the finding from model 1

(Table 2), which showed that mothers’ likelihood of being a

current smoker did not change significantly over 6–24 months

postpartum period. Mothers who breastfed their child were

significantly less likely to be a smoker, with an adjusted odds

ratio of 0.10 (95 % CI 0.02–0.68) after adjustment for part-

ner’s smoking status, and mother’s educational level.

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Model 3

Similar to mothers, the partner’s smoking status was

associated with their educational level, and the mother’s

smoking status (Table 4). But, interestingly, the partner’s

likelihood of being a current smoker significantly

decreased at 6 (AOR 0.34, 95 % CI 0.13–0.94) and

24 months postpartum (AOR 0.22, 95 % CI 0.07–0.69),

Table 2 Factors associated

with first-time mothers being

smokers using multivariable

two-level logistic random-

intercept model

� P value for trend testa Crude odds ratiob Odds ratio adjusted by

variables in the tablec HSC/TAFE refer to high

school certificate/technical and

further education

Variables ORa 95 % CI P AORb 95 % CI P

Time 0.002� 0.004�

Late pregnancy _ _

6 months postpartum 5.36 1.62–17.75 3.96 1.30–12.06

1 year postpartum 11.35 3.18–40.54 6.19 1.84–30.90

2 years postpartum 9.18 2.49–33.86 6.58 1.86–23.23

Partners’ smoking status \0.0001 \0.0001

No _ _

Yes 17.21 4.59–64.61 13.01 3.23–52.46

Education at being pregnant \0.0001 \0.0001

School certificate/lower _ _

HSC/TAFEc/University 0.003 3e-4–0.04 0.007 6e-4–0.08

Age at being pregnant 0.002

16–24 _

25–29 0.02 0.002–0.18

C30 0.06 0.005–0.69

Marital status 0.096

Other _

Married/de-factor partner 0.19 0.03–1.34

Country of birth 0.018

Other _

Australia 14.81 1.59–137.98

Table 1 Mothers’ smoking

status at late pregnancy by

demographics

a Does not add to 201 due to

missing valueb HSC/TAFE refer to high

school certificate/technical and

further education

* Chi squared test

Variables Total na (%) Current smokers

n (raw %)

P*

Age 0.001

16–24 85 (43) 24 (28)

C25 114 (57) 11 (10)

Marital status 0.096

Married/de-factor partner 174 (88) 27 (16)

Other 24 (12) 7 (29)

Employment status 0.021

Employed 109 (55) 13 (12)

Other 90 (45) 22 (24)

Household yearly income 0.43

\40,000 47 (25) 11 (23)

40,000–\80,000 65 (35) 9 (14)

C80,000 73 (40) 13 (18)

Country of birth 0.051

Australia 135 (68) 28 (21)

Other 63 (32) 6 (10)

Education \0.0001

Primary school/school certificate 44 (22) 18 (41)

HSC/TAFEb/University 154 (78) 17 (11)

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Table 3 Factors associated

with first-time mothers being

smokers after giving birth using

multivariable two-level logistic

random-intercept model

� P value for trend testa Crude odds ratiob Odds ratio adjusted by

variables in the tablec HSC/TAFE refer to high

school certificate/technical and

further education

Variables ORa 95 % CI P AORb 95 % CI P

Time 0.35�

6 months postpartum _

1 year postpartum 2.20 0.68–7.17

2 years postpartum 1.98 0.58–6.74

Current breastfeeding 0.017 0.018

No _ _

Yes 0.08 0.01–0.64 0.10 0.02–0.68

Partners’ smoking status \0.0001 0.002

No _ _

Yes 22.03 4.41–109.92 11.35 2.49–51.7

Education at late pregnancy \0.0001 0.001

School certificate/lower _ _

HSC/TAFEc/University 0.001 3e-5–0.02 0.01 0.0008–0.14

Age at late pregnancy 0.003

16–24 _

25–29 0.01 0.0007–0.15

C30 0.05 0.003–0.90

Marital status 0.014

Other _

Married/de-factor partner 0.01 0.0005–0.42

Country of birth 0.007

Other _

Australia 30.21 2.49–366

Table 4 Factors associated

with partners’ smoking using

multivariable two-level logistic

random-intercept model

� P value for trend testa Crude odds ratiob Odds ratio adjusted by

variables in the tablec HSC/TAFE refer to high

school certificate/technical and

further education

Variables ORa 95 % CI P AORb 95 % CI P

Time 0.03� 0.02�

Late pregnancy _ _

6 months postpartum 0.44 0.15–1.30 0.34 0.13–0.94

1 year postpartum 0.82 0.27–2.48 0.56 0.20–1.56

2 years postpartum 0.22 0.06–0.73 0.22 0.07–0.69

Mothers’ smoking status 0.002 \0.0001

No _ _

Yes 8.19 2.22–30.24 17.99 3.54–91.51

Partner’ education \0.0001 \0.0001

School certificate/lower _ _

HSC/TAFEc/University 0.0005 5e-5–0.006 0.009 0.0006–0.11

Partner age \0.0001

16–24 _

25–29 0.0008 6e-5–0.01

C30 0.001 9e-5–0.01

Partner country of birth 0.008

Other _ _

Australia 0.07 0.01–0.50

Marital status 0.14

Other _

Married/de-factor partner 0.23 0.03–1.60

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compared with the smoking status at late pregnancy, except

for at 12 months postpartum. The smoking rates of partners

before and after the birth of a new baby were 40 and 33 %,

respectively.

Model 4

The analysis also showed that the rate of a having smoke-

free home was higher postpartum (98 %) than in late

pregnancy (87 %). The likelihood of instituting a smoke-

free home was significantly increased after the birth of a

new baby. Families with mothers who were employed

(AOR 3.34, 95 % CI 1.24–9.05), or partners who had

higher education (HSC/TAFE or higher) (AOR 2.74, 95 %

CI 1.01–7.47) were much more likely to institute a smoke-

free home.

Discussion

In this study we found significant proportions of first-time

mothers and their partners still smoked during pregnancy

and alarmingly, the rate of smoking among the mothers

significantly increased after giving birth. Mothers’ smoking

status was associated with breastfeeding, educational level

and their partner’s smoking status. These findings are

generally consistent with existing evidence [4, 5, 9, 10, 15,

20]. A possible explanation of the high postpartum smok-

ing rate may be that having a new born baby could lead to a

self-perceived stressful situation for first-time mothers that

then triggers them to smoke [6, 8].

It has been suggested that smoking cessation programs

for pregnant women should include partners [5, 10, 15,

26]. Surprisingly, few existing studies reported part-

ners’smoking status during mothers’ pregnancy and the

postpartum period. Two studies found that the partners’

smoking status did not change significantly during the

mothers’ pregnancy and in the postpartum period [27, 28],

but they used cross-sectional data and did not investigate

the contributing factors of partners’ smoking during

pregnancy and postpartum. Yet, our study found that

encouragingly, the partners’ likelihood of being a smoker

decreased significantly after the birth of their child and

remained lower postpartum. Possible explanations may be

that the birth of a new baby increases both caring and

economic burdens for partners and that the fatherhood

role triggered modification of risk-taking behaviours [29].

A qualitative study [19] stated that many men recognized

that their smoking could no longer be viewed as an

individual activity in which they were free to engage

before being a father. Social and maternal pressure to

protect infants from smoking requires the fathers to sep-

arate their smoking from fathering.

As shown in previous studies, mothers’ smoking status

was influenced by partners’ smoking status [5, 8–10, 15,

20]. A study concluded that partners’ smoking was a major

determinant for changes in mothers’ smoking behaviour

during and after pregnancy [30]. Our study also found that

mothers’ and partners’ smoking are associated. Hence, to

be effective, smoking cessation interventions need to target

both mothers and their partners.

Our study also found an inverse relationship between

postpartum smoking and breastfeeding, which was sup-

ported by previous cross-sectional or short-term follow-up

studies [11–17]. Surprisingly, there have been few studies

looking into the effect of combined smoking cessation and

breastfeeding promotion programs. Few breastfeeding

programs have taken account of the particular needs of

women who smoke. Midwives often consider breastfeeding

promotion as part of their role, irrespective of the woman’s

smoking status. There is a need for the development of

health promotion programs including both components of

smoking cessation and breastfeeding promotion for women

during pregnancy and early postpartum.

One of main strengths of this study was that we used a

longitudinal cohort design with 2 year follow-up and four

data collection points and therefore we were able to

investigate the changes in relation to smoking status over

the 2 year period from late pregnancy to 24 months post-

partum. The use of two-level logistic random-intercept

models in order to investigate the contributing factors for

both mothers’ and partners’ smoking allowed us to deal

with the imbalance caused by missing data and increase the

precision of estimates [31]. However, this study is subject

to several limitations. It did not assess mothers’ stress level

after giving birth, which could interfere with the ability to

maintain smoking abstinence [6, 8]. Data on mothers’ and

partners’ knowledge about infant exposure to tobacco

smoke were not collected. The generalisability may also be

limited due to the locality of the study area. Another lim-

itation is loss to follow-up, although this was minimised by

using two-level logistic random-intercept models [31]. The

absence of data on other adults living in the household and

other substance use was another limitation to the study. In

addition, the study did not take full advantage of the lon-

gitudinal data by time-lagging their predictor variables.

Despite the limitations of this study, the findings are

useful in informing the development of family-based

interventions regarding smoking cessation and promoting

the health of children and their families. Since the smoking

rates of mothers are likely to increase after giving birth,

smoking cessation programs should not just focus on the

pregnancy but also include the early postpartum period, in

particular, the first 6 months postpartum. In addition,

smoking cessation program should have a greater focus on

those with lower levels of education.

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Acknowledgments This is part of the Healthy Beginnings Trial

funded by the Australian National Health and Medical Research

Council (ID number: 393112). We wish to thank all the families for

their participation in this study. We also thank members of the project

team based at Health Promotion Service, South Western Sydney &

Sydney Local Health Districts.

Conflict of interest The authors declare that they have no com-

peting interests in this study.

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