Featured articles 2012

Maternal smoking during pregnancy and reproductive health of daughters: A follow-up study spanning two decades.

Maternal lifestyle during pregnancy may have a programming effect on daughters’ reproductive health, but studies report conflicting results. The aim of this study was to investigate the associations between in utero exposure to cigarette smoke and markers of long-term reproductive health.

965 women from a Danish cohort established in 1988-89 provided around 30th pregnancy week information on lifestyle factors during pregnancy, including smoking habits. In 2008, 367 (85%) daughters completed a questionnaire on reproductive health of whom 267 (61%) attended a clinical examination. At examination blood samples were analysed for reproductive hormones, interviews on menstrual pattern were carried out, and number of follicles were determined by transvaginal ultrasound. The daughters were divided into 3 exposure groups according to the level of maternal smoking during first trimester (none, low, high).
We found an inverse association between prenatal exposure to cigarette smoke and age of menarche. Daughters exposed to ≥ 10 cigarettes/day debuted with 6.5 (95 % CI: -10.7 to -2.2) months earlier age of menarche. There was a tendency towards lower levels of testosterone and DHEAS and higher levels of FSH with increasing in utero exposure to smoke, but the results were not statistically significant. Maternal cigarette smoking during pregnancy was not associated with follicle number, cycle length or other reproductive hormones.
In utero exposure to maternal cigarette smoke may lead to earlier age of menarche and altered hormonal profile in young women.

Ernst A,  Kristensen SL, Toft G,  Thulstrup AM, Håkonsen LB, Olsen SF, Ramlau-Hansen C.H. Maternal smoking during pregnancy and reproductive health of daughters. A follow-up study spanning two decades. Human Reproduction 2012; 27(12):3593-600.


Intake of low-fat yoghurt during pregnancy may increase risk of asthma and hay fever in the child

Dairy products contain many different nutrients, among them fatty acids that may be beneficial for human health. While some studies have looked at dairy intake during pregnancy and development of asthma and allergies in children, their results are unclear.

Using information from over 60,000 women, we examined the relation between consumption of various dairy products (including milk and yoghurt with different fat content and additives) in the second trimester and child asthma and hay fever. We found that high intake of whole milk in pregnancy appeared to protect against early-life asthma, while semi-skimmed milk increased the risk of early asthma.

Additionally, women who ate higher amounts of low-fat yoghurt while pregnant tended to have children with more asthma and hay fever. Since the study focused on intake of whole foods, pinpointing the nutrient or nutrients responsible for these relations is difficult. We speculate that components specific to low-fat yoghurt, such as artificial sweeteners or other additives, may be of interest and hope to further examine these in future studies.

Maslova E, Strøm M, Halldorsson TI, Olsen SF. Low-fat yoghurt intake in pregnancy associated with increased child asthma and allergic rhinitis risk: a prospective cohort study. J Nutritional Science 2012;1(5): 1-11.


Eating peanuts and tree nuts during pregnancy may decrease risk of asthma and hay fever in the child

Peanuts and tree nuts carry a strong allergenic potency that may be transmitted do the child during pregnancy. Several authorities have recommended that pregnant women stay away from nuts and peanuts to avoid inducing allergy in the (unborn) child.

However, in the past years recommendations about peanut and tree nut intake during pregnancy have been conflicted, leaving mothers and clinicians alike confused. We therefore decided to examine the relation between maternal intake of peanuts and tree nuts in mid-pregnancy and asthma and hay fever diagnoses in the children.

Using dietary information from ~ 60,000 Danish women, we found that women who ate peanuts and tree nuts weekly (compared to women who did not eat peanuts/tree nuts) were less like to have their children diagnosed with asthma in both early and later childhood (up to age 7). Eating tree nuts during pregnancy also appeared to protect against hay fever in the child.

These results suggest that eating peanuts and tree nuts during pregnancy does not increase risk of child asthma and hay fever and may even protect the children from developing these conditions. 

Maslova E, Granstrom C, Hansen S, Petersen SB, Strøm M, Willett W, Olsen SF: Peanut and tree nut consumption during pregnancy and allergic disease in children—should mothers decrease their intake? Longitudinal evidence from the Danish National Birth Cohort, J Allergy Clin Immunol 2012;130(3):724-32.