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Preeclampsia more frequent with asthma sufferers
Women with asthma suffer more often from preeclampsia (PE) and run a higher risk of giving birth to underweight babies. These and other complications during pregnancy and delivery can not be explained by hereditary or environmental factors, according to a study from Karolinska Institutet published in The Journal of Allergy and Clinical Immunology: In Practice.
Asthma is a common disease caused by chronic inflammation in the lungs with symptoms of coughing and breathlessness, and affects between 8-10 percent of women of childbearing age in Sweden.
Using data from Swedish (1) birth, (2) prescribed drug and (3) patient registers, researchers at Karolinska Institutet have been able to examine the link between asthma in pregnant women and pregnancy/delivery outcomes. Studying more than 1 million births by just over 700,000 women between 2001 and 2013, they found that 10 percent of these babies born to a mother with asthma.
"Four percent of all pregnant women develop preeclampsia. We found that the risk of preeclampsia is 17 percent higher in women with asthma compared to women without asthma"
Additionally, women with asthma were more likely to have underweight babies, instrumental deliveries or deliveries by forceps, caesarean sections and shorter pregnancies.
To ascertain whether the complications could be attributed to hereditary or environmental factors, the researchers also identified the women's asthma-free cousins and sisters who had given birth during the same period. On comparing the groups they found that the correlations between maternal asthma and complications during pregnancy and delivery held.
"It seems to be the asthma per se that causes these complications. This means that well-controlled asthma during pregnancy could reduce the relative incidence this was indeed the case." of complications during pregnancy and childbirth. In an earlier study we saw that"
Asthma is associated with several adverse pregnancy and perinatal outcomes. Familial factors may confound these associations.
To examine the role of measured and unmeasured confounding by conducting a study that compared differentially exposed cousins and siblings from the same families.
We retrieved data on adverse pregnancy outcomes, prescribed drugs, and physician-diagnosed asthma from nationwide registers for all women in Sweden with singleton births between 2001 and 2013. Logistic and linear regression estimated the association between maternal asthma and several outcomes in the whole population and within differently exposed pregnant relatives.
In total, 1,075,153 eligible pregnancies were included and 10.1% of the study population had asthma. We identified 475,200 cousin and 341,205 sister pregnancies. Women with asthma had increased risks for preeclampsia (adjusted odds ratio [aOR], 1.17; 95% CI, 1.13-1.21), emergency cesarean section (aOR, 1.24; 95% CI, 1.22-1.27), and having a child small for gestational age (aOR, 1.18; 95% CI, 1.12-1.23). In the conditional regression analyses, after adjustment for familial factors, the associations remained: preeclampsia in cousins (aOR, 1.16; 95% CI, 1.07-1.25) and siblings (aOR, 1.23; 95% CI, 1.08-1.38), emergency cesarean section in cousins (aOR, 1.28) and siblings (aOR, 1.21), and small for gestational age in cousins (aOR, 1.17) and siblings (aOR, 1.13).
Factors shared by siblings and cousins do not seem to explain the observed association between maternal asthma and adverse pregnancy outcomes. This implies that targeting the asthma disease will continue to be important in reducing risks for adverse outcomes in pregnancy.
Asthma, Epidemiology, Family design, Pregnancy, Pregnancy outcomes
Gustaf Rejnö MD, Cecilia Lundholm MSc, Kjell Larsson MD PhD, Henrik Larsson PhD,Paul Lichtenstein PhD, Brian M. D'Onofrio PhD, Sissel Saltvedt MD PhD, Catarina Almqvist MD PhD.
The authors declare no competing financial interests. The study was financed by the Swedish Research Council, Stockholm County Council, FORTE, the Strategic research programme in Epidemiology and the Swedish Heart and Lung Foundation.
Publication: "Adverse Pregnancy Outcomes in Asthmatic Women: A Population-Based Family Design Study". Gustaf Rejnö, Cecilia Lundholm, Kjell Larsson, Henrik Larsson, Paul Lichtenstein, Brian D'Onofrio, Sissel Saltvedt, Catarina Almqvist. Journal of Allergy and Clinical Immunology: In Practice (published by Elsevier), online 4 October 2017, doi: 10.1016/j.jaip.2017.07.036.
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Women with asthma were more likely to have underweight babies, instrument deliveries by forceps, caesarean sections and shorter pregnancies.. Image Credit: from the public domain