Maternal bipolar disorder increased low birthweight and preterm births:
A nationwide population-based study
Hsin-Chien Leea,b, Herng-Ching Linc,⁎
aTaipei Medical University-Shuang Ho Hospital, Department of Psychiatry & Sleep Center, Taipei, Taiwan
bTaipei Medical University, School of Medicine, Department of Psychiatry, Taipei, Taiwan
cSchool of Health Care Administration, Taipei Medical University, 250 Wu-Hsing St., Taipei 110, Taiwan
a r t i c l e i n f o a b s t r a c t
Received 7 January 2009
Received in revised form 21 May 2009
Accepted 21 May 2009
Available online 6 June 2009
Objective: To investigate pregnancy outcomes, including low birthweight, preterm births, and
small-for-gestational-age (SGA) among womenwith bipolar disorder, schizophrenia compared
with women with no history of mental illness using nationwide population-based data.
Methods: This study linked the Taiwan National Health Insurance Research Dataset with the
national birth certificate registry. A total of 528,398 singleton births between 2001 and 2003
were included; 337 were diagnosed with bipolar disorder. Multivariate logistic regression
analyses were carried out to examine the relationship between maternal bipolar disorder,
schizophrenia and the odds of low birthweight, preterm births, and SGA, after adjusting for
characteristics of infant, mother and father.
Results: It shows that pregnant women with bipolar disorder were more likely to have LBW
infants (9.8% vs. 5.7%), preterm births (14.2% vs. 6.9%) and SGA (22.3% vs.15.7%) than pregnant
womenwith no historyof mental illness. The adjusted odds of low birthweight for womenwith
bipolar disorder was 1.66 times (95% CI, 1.16–2.38) that of women with no history of mental
illness. In terms of preterm births and SGA, the adjusted odds ratios were 2.08 (95% CI, 1.53–
2.83) and 1.47 (95% CI, 1.14–1.91) respectively, for women with bipolar disorder, compared to
their counterparts with no history of mental illness.
Conclusions: We conclude that women with bipolar disorder had increased risk of low
birthweight, preterm births, and SGA than women without a history of mental illness. More
active monitoring and early intervention to counter potential adverse pregnancy outcomes for
pregnant women with bipolar disorder should be initiated.
© 2009 Elsevier B.V. All rights reserved.
Mothers suffering from severe mental disorders are more
likely to have adverse pregnancy outcomes. For example,
Howardet al. reported that womenwitha historyof psychotic
disorders had a higher proportion of stillbirths and neonatal
deaths compared with other women (Howard et al., 2004).
Previous studies also found that schizophrenia women have
increased risk of preterm delivery, stillbirth and low birth-
weight (LBW) (Nilsson et al., 2002; Rifkin et al., 1994;
Bennedsen et al., 1999; Sacker et al., 1996). Besides schizo-
phrenia, MacCabe et al. (2007) observed that mothers with
affective disorders had elevated risk for preterm birth and
small or growth-retarded babies. Webb et al. likewise
reported higher risk of fatal birth defects associated with
maternal affective disorder (Webb et al., 2007). However, few
studies to date have focused specifically on women with
Jablensky et al. (2005) have examined the characteristics
of infants born to women with schizophrenia, bipolar
disorder, or major depression in Western Australia. They
found an increased risk of obstetric complications among
womenwith schizophrenia and womenwith bipolardisorder.
However, no increased risk of LBW and preterm birth was
Journal of Affective Disorders 121 (2010) 100–105
⁎ Corresponding author. Tel.: +886 2 2736 1661x3613; fax: +886 2 2378
E-mail address: firstname.lastname@example.org (H.-C. Lin).
0165-0327/$ – see front matter © 2009 Elsevier B.V. All rights reserved.
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smoking (hazard ratio=12.3) (Wilens et al., 2008). Another
study by Gonzalez-Pinto et al. even indicated that bipolar
disorder (in both genders) was significantly associated
(OR=4.4) with heavy smoking (more than 1 pack per day)
was not available in our dataset. But the study by MacCabe et al.
(2007) did show that the relationship between mothers with
affective disorder and elevated risk of adverse pregnancy
outcomes persists even after adjusting for smoking. Therefore,
smoking may not be the sole cause of this relationship.
The treatment for bipolar disorder itself, whether persis-
tent or discontinued, during pregnancy may be another
potential factor contributing to this relationship. At present,
it is still difficult to estimate the risks and benefits of taking
such medication during pregnancy, due to inadequate data
(Wisner et al., 2000).
The strengths of this study include its use of nationwide
population-based datasets linking the NHIRD with birth
certificates and the adjusting for important characteristics of
mother, father and infant. However, the findings of this study
should be interpreted within the context of three limitations.
First, we identified mothers diagnosed with bipolar disorder
from the registry of catastrophic illness released by the Bureau
of the NHI, potential sampling bias existed, such as a financial
incentive for bipolar patients with low socioeconomic status to
validity and reliability, there was no standardized diagnostic
algorithm ofbipolardisorder inserviceclaimsdata.Inaddition,
this dataset did not allow us to account for differences in the
severity of bipolar disorder among patients. Thirdly, informa-
tion on mothers' smoking history, substance abuse, alcohol
consumption, nutrition and body mass index are not available
through our datasets.
Despite these limitations, this study found that women
with bipolar disorder had increased risk of LBW and preterm
births than women without bipolar disorder, after adjusting
for potential confounders. Clinicians should be aware of the
increased risk of adverse pregnancy outcomes among these
women. More active monitoring and early intervention to
counter potential LBW and preterm births should be initiated
for women with bipolar disorder. In addition, further studies
are needed to elucidate the underlying mechanisms linking
bipolar disorder among mothers and fetal development.
Role of funding source
Conflict of interest
No conflict declared.
This study was supported by grant 98TMU-SHH-05 from
the Taipei Medical University-Shuang Ho Hospital.
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H.-C. Lee, H.-C. Lin / Journal of Affective Disorders 121 (2010) 100–105