Pregnancy planning, smoking behaviour during pregnancy, and neonatal outcome: UK Millennium Cohort Study.

BACKGROUND: Pre-pregnancy health and care are important for the health of the future generations. Smoking during pregnancy has been well-researched and there is clear evidence of harm. But there has been little research on the health impact of planning for pregnancy. This study aims to investigate the independent effects of pregnancy planning and smoking during pregnancy on neonatal outcome. METHODS: This analysis made use of data from the UK Millennium Cohort Study. The study sample consisted of 18,178 singleton babies born in UK between 2000 and 2001. The neonatal outcomes of interest were low birthweight (<2.5 Kg) and pre-term birth (<37 completed weeks gestation). Logistic regression was used to estimate the association between pregnancy planning and/or smoking and neonatal outcome. Adjusted odds ratios were used to calculate population attributable risk fractions (PAFs). RESULTS: 43% of mothers did not plan their pregnancy and 34% were smoking just before and/or during pregnancy. Planners were half as likely to be smokers just before pregnancy, and more likely to give up or reduce the amount smoked if smokers. Unplanned pregnancies had 24% increased odds of low birth weight and prematurity compared to planned pregnancies (AORLBW1.24, 95% CI 1.04-1.48; AORPREM1.24, 95% CI 1.05-1.45), independent of smoking status. The odds of low birth weight for babies of mothers who were smoking just before pregnancy was 91% higher than that of mothers who were not (AORLBW1.91, 95% CI 1.56-2.34). Women who quit or reduced the amount smoked during pregnancy lowered the risk of a low birth weight baby by one third (AORLBW0.66, 95% CI 0.51-0.85) compared with women whose smoking level did not change. Smaller effects were found for prematurity. If all women planned their pregnancy and did not smoke before or during pregnancy, 30% of low birthweight and 14% of prematurity could, in theory, be avoided. CONCLUSIONS: Planning a pregnancy and avoiding smoking during pregnancy has clear, independent, health benefits for babies. Quitting or reducing the amount smoked during pregnancy can reduce the risk of low birthweight

Placental vascular defects in compromised pregnancies: effects of assisted reproductive technologies and other maternal stressors

Many factors negatively affect pregnancy establishment and subsequent fetal growth and development, including maternal factors such as nutritional stress, age, body mass index, and genetic background, and external factors including environmental stress, psychosocial stress, multiple fetuses, medical conditions (e.g., polycystic ovary syndrome), lifestyle choices (e.g., alcohol consumption, smoking), and assisted reproductive technologies. These same factors have similar consequences for placental growth and development, including vascular development. We and others have shown that placental vascular development begins very early in pregnancy and determines, to a large extent, placental function—that is, the magnitude of the increase in placental blood flow and thus nutrient transport to the fetus. During the peri-implantation period and also later in pregnancy, cloned (somatic cell nuclear transfer) embryos exhibit a variety of placental defects including reduced vascularization and altered expression of angiogenic factors. Although placental defects are less pronounced in pregnancies resulting from the transfer of in vitro fertilized embryos, we and others have recently demonstrated that vascularization, expression of angiogenic factors, sex steroid receptors, several epigenetic markers, and growth of utero-placental tissues all were altered during early pregnancy after transfer of embryos obtained through natural mating, in vitro fertilization, or other assisted reproductive techniques. These observations are in agreement with the recent reports that in humans even singleton pregnancies established with assisted reproductive techniques are at increased risk of preterm delivery and low birth weight, and seem especially relevant considering the rapidly expanding use of these techniques in humans and animals