News briefs

Long term risks and benefits of caesarian deliveries

Researchers from the UK and the School of Women’s and Infants’ Health at the University of Western Australia have conducted a large literature review, published in PLoS Medicine, which identified one randomised controlled trial and 79 cohort studies (29 928 274 participants overall) that assessed long term outcomes after caesarean delivery and vaginal delivery. Compared with vaginal deliveries, caesarean deliveries were found to be associated with a decreased risk of urinary incontinence (1024/7306 caesarean delivery v 7713/51 594 vaginal delivery; odds ratio [OR], 0.56; 95% confidence interval [CI], 0.47–0.66) and pelvic prolapse (116/4898 caesarean delivery v 2055/34 310 vaginal delivery; OR, 0.29; 95% CI, 0.17–0.51). Children born by caesarean delivery had an increased risk of asthma for up to 12 years (4788/124 668 caesarean delivery v 23 308/763 292 vaginal delivery; OR, 1.21; 95% CI, 1.11–1.32) and of obesity up to 5 years of age (834/6645 caesarean delivery v 5295/57 468 vaginal delivery; OR, 1.59; 95% CI, 1.33–1.90). Pregnancy after caesarean delivery was associated with an increased risk of miscarriage (2060/19 106 previous caesarean delivery v 12 663/132 306 previous vaginal delivery; OR, 1.17; 95% CI, 1.03–1.32), stillbirth (496/118 192 previous caesarean delivery v 1905/585 370 previous vaginal delivery; OR, 1.27; 95% CI, 1.15–1.40), placenta praevia (5039/1 025 692 previous caesarean delivery v 16 679/6 076 000 previous vaginal delivery; OR, 1.74; 95% CI, 1.62–1.87), placenta accreta (44/66 241 previous caesarean delivery v 188/638 867 previous vaginal delivery), and placental abruption (6047/858 208 previous caesarean delivery v 23 855/4 808 952 previous vaginal delivery; OR, 1.38; 95% CI, 1.27–1.49). Because the findings were predominantly based on observational data, causation cannot be inferred and the findings should be interpreted with caution. Further, the authors were not able to analyse the data by planned (elective) or emergency caesarean delivery.

http://journals.plos.org/plosmedicine/article?id=10.1371/journal.pmed.1002494

One cigarette per day increases heart disease and stroke risk

No safe level of smoking exists, and smokers should aim to quit instead of cutting down, say the authors of a literature review published in The BMJ. The researchers from University College London found that smoking just one cigarette a day was associated with a higher risk of developing coronary heart disease and stroke than expected: about half the risk of smoking 20 cigarettes per day. Individual studies have previously reported that smoking only one to five cigarettes per day is associated with a higher than expected risk of heart disease. To investigate this further, the researchers conducted a meta-analysis of 141 studies and estimated the relative risks for smoking one, five, or 20 cigarettes per day. They found that men who smoked one cigarette per day had 46% of the excess risk of heart disease and 41% of the excess risk of stroke associated with smoking 20 cigarettes per day (much higher than the expected 5%). For women, those who smoked one cigarette per day had 31% of the excess risk of heart disease and 34% of the excess risk of stroke associated with smoking 20 cigarettes per day. Women’s heart disease risk was more than double with one cigarette per day when only studies that controlled for several factors were included in the analysis. In a linked editorial, Kenneth Johnson, Adjunct Professor at the University of Ottawa outlined the major public health implications of these results, and said that “only complete cessation is protective and should be emphasised by all prevention measures and policies”.

http://www.bmj.com/content/360/bmj.j5855

http://www.bmj.com/content/360/bmj.k167