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Preterm birth and future risk of maternal cardiovascular disease - is the association independent of smoking during pregnancy?

Ngo AD, Chen JS, Figtree G, Morris JM, Roberts CL - BMC Pregnancy Childbirth (2015)

Bottom Line: A further adjustment for maternal smoking attenuated, but did not eliminate, the associations.Smoking during pregnancy was also independently associated with maternal CVD risks, with associations being stronger for mothers who smoked during last pregnancy (AHR = 2.07 [1.93-2.23]) than mothers who smoked during a prior pregnancy (AHR = 1.64 [1.41-1.90]).Associations of preterm birth and maternal CVD risk are independent of maternal smoking during pregnancy.

View Article: PubMed Central - PubMed

Affiliation: Clinical and Population Perinatal Health Research, Kolling Institute, University of Sydney at Royal North Shore Hospital, St Leonards, New South Wales, NSW 2065, Australia. ducanhnguyet@yahoo.com.

ABSTRACT

Background: While the association of preterm birth and the risk of maternal cardiovascular disease (CVD) has been well-documented, most studies were limited by the inability to account for smoking during pregnancy - an important risk factor for both preterm birth and CVD. This study aimed to determine whether the increased future risk of maternal cardiovascular disease (CVD) associated with preterm birth is independent of maternal smoking during pregnancy.

Methods: A population-based record linkage study of 797,056 women who delivered a singleton infant between 1994 and 2011 in New South Wales, Australia was conducted. Birth records were linked to the mothers' subsequent hospitaliation or death from CVD. Preterm births were categorised as late (35-36 weeks), moderate (33-34 weeks), or extreme (≤32 weeks); and as spontaneous or indicated. Cox proportional hazard regression was used to estimate adjusted hazard ratios (AHR) [95 % CI].

Results: During the study period, 59,563 women (7.5 %) had at least one preterm birth. After adjustment for CVD risk factors other than smoking, AHR [95 % CI] of CVD among women who ever had a preterm birth was 1.78 [1.61-1.96]. Associations were greater for extreme (AHR = 1.98 [1.63-2.42]) and moderate (AHR = 2.06 [1.69-2.51]) than late preterm birth (AHR = 1.63 [1.44-1.85]), for indicated (AHR = 2.04 [1.75-2.38]) than spontaneous preterm birth (AHR = 1.65 [1.47-1.86]), and for having ≥ two (AHR = 2.29[1.75-2.99]) than having one preterm birth (AHR = 1.73[1.57-1.92]). A further adjustment for maternal smoking attenuated, but did not eliminate, the associations. Smoking during pregnancy was also independently associated with maternal CVD risks, with associations being stronger for mothers who smoked during last pregnancy (AHR = 2.07 [1.93-2.23]) than mothers who smoked during a prior pregnancy (AHR = 1.64 [1.41-1.90]).

Conclusions: Associations of preterm birth and maternal CVD risk are independent of maternal smoking during pregnancy. This underscores the importance of smoking cessation in reducing CVD and suggests that a history of preterm delivery (especially if severe, indicated or recurrent) identifies women who could be targeted for CVD screening and preventative therapies.

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Related in: MedlinePlus

Flow chart of selection of women for analysis
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Fig1: Flow chart of selection of women for analysis

Mentions: Of 912,801 women who gave a singleton birth during the study period, 104,952 women (11.6 %) who ever had a pregnancy complicated by chronic hypertension (2.3 %) or pregnancy hypertension (9.3 %), and 845 women with a CVD before last birth or having a CVD event within 42 days of last birth were excluded. A further 9,948 women (1.1 %) were subsequently excluded due to missing covariate information (Fig. 1). After all exclusions, 797,056 women remained for the analysis. The median age of women at last birth was 31 years (inter-quartile range: 27–35).Fig. 1


Preterm birth and future risk of maternal cardiovascular disease - is the association independent of smoking during pregnancy?

Ngo AD, Chen JS, Figtree G, Morris JM, Roberts CL - BMC Pregnancy Childbirth (2015)

Flow chart of selection of women for analysis
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4491219&req=5

Fig1: Flow chart of selection of women for analysis
Mentions: Of 912,801 women who gave a singleton birth during the study period, 104,952 women (11.6 %) who ever had a pregnancy complicated by chronic hypertension (2.3 %) or pregnancy hypertension (9.3 %), and 845 women with a CVD before last birth or having a CVD event within 42 days of last birth were excluded. A further 9,948 women (1.1 %) were subsequently excluded due to missing covariate information (Fig. 1). After all exclusions, 797,056 women remained for the analysis. The median age of women at last birth was 31 years (inter-quartile range: 27–35).Fig. 1

Bottom Line: A further adjustment for maternal smoking attenuated, but did not eliminate, the associations.Smoking during pregnancy was also independently associated with maternal CVD risks, with associations being stronger for mothers who smoked during last pregnancy (AHR = 2.07 [1.93-2.23]) than mothers who smoked during a prior pregnancy (AHR = 1.64 [1.41-1.90]).Associations of preterm birth and maternal CVD risk are independent of maternal smoking during pregnancy.

View Article: PubMed Central - PubMed

Affiliation: Clinical and Population Perinatal Health Research, Kolling Institute, University of Sydney at Royal North Shore Hospital, St Leonards, New South Wales, NSW 2065, Australia. ducanhnguyet@yahoo.com.

ABSTRACT

Background: While the association of preterm birth and the risk of maternal cardiovascular disease (CVD) has been well-documented, most studies were limited by the inability to account for smoking during pregnancy - an important risk factor for both preterm birth and CVD. This study aimed to determine whether the increased future risk of maternal cardiovascular disease (CVD) associated with preterm birth is independent of maternal smoking during pregnancy.

Methods: A population-based record linkage study of 797,056 women who delivered a singleton infant between 1994 and 2011 in New South Wales, Australia was conducted. Birth records were linked to the mothers' subsequent hospitaliation or death from CVD. Preterm births were categorised as late (35-36 weeks), moderate (33-34 weeks), or extreme (≤32 weeks); and as spontaneous or indicated. Cox proportional hazard regression was used to estimate adjusted hazard ratios (AHR) [95 % CI].

Results: During the study period, 59,563 women (7.5 %) had at least one preterm birth. After adjustment for CVD risk factors other than smoking, AHR [95 % CI] of CVD among women who ever had a preterm birth was 1.78 [1.61-1.96]. Associations were greater for extreme (AHR = 1.98 [1.63-2.42]) and moderate (AHR = 2.06 [1.69-2.51]) than late preterm birth (AHR = 1.63 [1.44-1.85]), for indicated (AHR = 2.04 [1.75-2.38]) than spontaneous preterm birth (AHR = 1.65 [1.47-1.86]), and for having ≥ two (AHR = 2.29[1.75-2.99]) than having one preterm birth (AHR = 1.73[1.57-1.92]). A further adjustment for maternal smoking attenuated, but did not eliminate, the associations. Smoking during pregnancy was also independently associated with maternal CVD risks, with associations being stronger for mothers who smoked during last pregnancy (AHR = 2.07 [1.93-2.23]) than mothers who smoked during a prior pregnancy (AHR = 1.64 [1.41-1.90]).

Conclusions: Associations of preterm birth and maternal CVD risk are independent of maternal smoking during pregnancy. This underscores the importance of smoking cessation in reducing CVD and suggests that a history of preterm delivery (especially if severe, indicated or recurrent) identifies women who could be targeted for CVD screening and preventative therapies.

Show MeSH
Related in: MedlinePlus