A study looks at the impact of a preterm birth on the mother's future risk of cardiovascular disease. Plus: Do shift work and physical labor negatively impact a woman's fertility? Also, are women who get a false-positive mammogram more likely to delay their future screenings?
Preterm delivery may put women at increased risk of cardiovascular disease (CVD) later in lifem according to a study in Circulation.
Researchers looked at the 70,182 parous women in Nurses’ Health Study II to examine the link between delivering an infant preterm (< 37 weeks) and CVD. They used multivariable Cox proportional-hazards to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for cardiovascular events (myocardial infarction and stroke, n = 949).
Following adjustment for age, race, parental education, and prepregnancy lifestyle and cardiovascular risk factors, a preterm delivery in a woman’s first pregnancy was linked with an increased risk of CVD (HR, 1.42; 95% CI, 1.16–1.72) when compared to women who had a term delivery (≥ 37 weeks) in their first pregnancy. When split into moderate preterm (≥ 32 to < 37 weeks) and very preterm (< 32 weeks), the HRs were 1.22 (95% CI, 0.96–1.54) and 2.01 (95% CI, 1.47–2.75), respectively.
Even among women who had first pregnancies uncomplicated by hypertensive disorders of pregnancy, the increased rate of CVD persisted in the very preterm group (HR, 2.01; 95% CI, 1.38–2.93). When compared to women with at least 2 pregnancies all delivered at term, women with a preterm first birth and at least 1 more later preterm birth had an HR for CVD of 1.65 (95% CI, 1.20–2.28). The link between moderate preterm first birth and CVD was accounted for in part by the development of changes in body mass index, type 2 diabetes, postpartum chronic hypertension, and hypercholesterolemia (proportion accounted for, 14.5%; 95% CI, 4.0–41.1), as was the very-preterm-CVD relationship (13.1%; 95% CI, 9.0–18.7).
The researchers concluded that preterm delivery was independently predictive of CVD and could prove useful in CVD efforts. Because only a relatively modest proportion of the association between preterm birth and CVD was accounted for with development of convention CVD risk factors, the researchers say that further research could help identify other pathways.
Night shifts, physical labor, and fecundity
Women who work at night and perform physically demanding jobs may have lower fecundity, according to researchers from Harvard University. Their findings, published in Occupational and Environmental Medicine, are from a first-of-its-kind study that looked at the association between occupational factors and markers of ovarian response in women of reproductive age.
Participants in the prospective cohort were 786 women aged 18 to 45 with mean body mass index (BMI) 23 who planned to use their own gametes and were being treated at an academic fertility center between 2004 and 2015. Unexplained infertility was the primary diagnosis for most of the patients and 80% had undergone examination for infertility but only 48% had previously been treated for the condition.
A questionnaire was used to collect information on the women’s occupational factors and electronic medical records were used to identify reproductive outcomes in the cohort. Compared with women who worked only day shifts, those who worked evening/night/rotating shifts had 2.3 fewer mature oocytes, on average (P<0.001). Moving heavy objects at work was associated with trends toward fewer total oocytes, mature oocytes, and antral follicles (P=0.08, P=0.07, and P=0.06, respectively).
The inverse association between heavy lifting and oocyte yield was stronger in women older than age 37 and with a BMI of at least 25 and when evening/night shift workers were considered as separate category (3.2 fewer mature oocytes in evening/night shift workers versus 8 in women working days). None of the occupational exposures were associated with Day 3 follicle-stimulating hormone or peak estradiol levels. Adjustment for total leisure time physical activity and smoking status did not affect the results.
Their results, the authors said, “suggest that occupational factors may be more specifically affecting oocyte production and quality, rather than accelerating ovarian ageing, in this study population of women attending a fertility centre.” They cautioned that it may not be possible to generalize the findings to couples conceiving without medical intervention and note that they were not able to control for other work factors that might have been correlated with shift and physically demanding work. “Future work in other studies is needed,” the researchers said, “to further disentangle the effects of rotating shift work with and without nights and current versus lifetime exposure to shift work on fecundity.”
Does a false-positive mammogram lead to delay in future screenings?
Following a false-positive result from a screening mammogram, women may be more likely to delay or even forgo subsequent screenings, according to a new study published in Cancer Epidemiology, Biomarkers & Prevention.
The researchers used data from women who had mammogram screenings through a large healthcare organization with multiple facilities in the greater Chicago metropolitan area, which covered 741,150 screening mammograms for 261,767 women.
Of the mammograms included, 650,232 produced true-negative results and 90,918 produced false-positive results. The likelihood of undergoing a subsequent mammogram was higher among women who had true-negative than those who had a false-positive result (85.0% vs 77.9%, P < 0.001). Median delay in being screened again was higher among women who had a false-positive result than a true-negative (13 months vs 3 months, P < 0.001). Additionally, women with a true-negative screening were 36% more likely to have a screening in the next 36 months than women who had a false-positive (hazard ratio = 1.36; 95% confidence interval, 1.35-1.37). Also women who have a false-positive mammogram are at increased risk of late-stage disease at time of diagnosis compared to those who have a true-negative mammogram (P < 0.001).
The investigators concluded that a false-positive mammogram is likely to cause a woman to delay subsequent screening, which could increase the 4-year cumulative risk of late-stage disease at time of diagnosis.