Prenatal exposures and the development of childhood wheezing illnesses

Abstract

Purpose of review To critically evaluate and summarize studies published between July 2015 and June 2016 linking prenatal exposures and the onset of childhood wheezing illnesses, and to discuss future research directions in this field. Recent findings The aggregated evidence indicates a consistent detrimental effect of prenatal exposure to parental smoking, outdoor air pollution, and maternal stress on childhood wheezing illnesses. Less consistent evidence suggests an adverse impact of maternal obesity during pregnancy and prenatal exposure to antibiotics on these outcomes. There is insufficient evidence to support an association between in utero exposure to acetaminophen or prenatal levels of specific nutrients (such as vitamin D, folic acid, or polyunsaturated fatty acids) and childhood wheezing illnesses. Summary Several common potentially modifiable prenatal exposures appear to be consistently associated with childhood wheezing illnesses (e.g., parental smoking, outdoor air pollution, and maternal stress). However, the effect of many other prenatal exposures on the onset of childhood wheezing illnesses remains unclear. The existing scientific evidence from the past year does not allow us to make any new recommendations on primary prevention measures. Intervention studies will best demonstrate whether changing the prenatal environment can prevent childhood wheezing illnesses and asthma.

Effect of Maternal Sleep, Physical Activity and Screen Time during Pregnancy on the Risk of Childhood Respiratory Allergies: a Gender-specific Study

“…Early life exposure in utero can affect fetal airway and lung development, as well as immune function. 30 As suggested by previous studies, maternal smoking, unqualified diet, vitamin D deficiency and exposure to air pollution has been found to be possible potential risk factors. 7,31−34 A retrospective follow-up study was conducted among 1201 Los Angeles women between 3 and 6 months after delivery, where it was shown that children whose mothers ate more fast food during pregnancy had a relative increased risk of asthma.…”

Development of allergic immunity in early life

“…Conversely, maternal obesity has profound effects on immune responses in the baby, giving rise to systemic inflammation as well as asthma. Maternal prenatal BMI is associated with increased incidence of wheezing and asthma …”

“…Maternal stress is a significant risk factor for wheezing in early life as well as development of asthma . This may be due to transfer of glucocorticoid hormone across the placenta, which has wide ranging effects on the immune system .…”

“…Maternal prenatal BMI is associated with increased incidence of wheezing and asthma. 131 There are multiple longitudinal studies that support the hypothesis that maternal, or paternal, smoking has a negative impact on pulmonary health in babies and greatly enhances the odds of developing recurrent wheeze or asthma. [132][133][134] Cigarette smoke exposure has been shown to increase expression of specific microRNAs in the blood concomitant with lower numbers of T-regulatory cells in maternal and cord blood, which was associated with an increased risk of atopic disease.…”

“…137 Maternal stress is a significant risk factor for wheezing in early life as well as development of asthma. 131,138 This may be due to transfer of glucocorticoid hormone across the placenta, which has wide ranging effects on the immune system. 139 Although it has been suggested that maternal stress impacts development of adaptive immune responses in neonates, with reduced humoral immunity and reduced capacity for Th1 responses, recent studies suggest that the effects may only be transient.…”