Maternal fatty acids and antioxidants in pregnancies complicated by asthma and their relationship to fetal growth.

Asthma is one of the leading respiratory diseases affecting pregnancies today. Its effects on the mother and on fetal growth in particular are of great interest since the development of the fetus is highly plastic at this crucial period of development. Since inflammation and oxidative stress inherent in asthma have been shown to affect maternal and fetal outcomes, it was therefore the primary aim of this thesis to characterise the maternal circulating levels of fatty acids and antioxidants and to investigate the potential relationships with maternal dietary intake and fetal and neonatal growth parameters between groups. As a part of a larger prospective study on asthma, 131 pregnant women; non-asthmatic control subjects (n=47) and asthmatic women (mild [n=31] & moderate/severe [n=53]), were recruited at their first antenatal visit to the John Hunter Hospital in Newcastle, Australia. Women completed a 24 hour dietary food recall questionnaire at each subsequent visit; gestational (G) weeks G18, G30 and G36, at which times blood was collected. Corticosteroid use and smoking were assessed by direct questioning by respiratory nurses. We found no differences in maternal characteristics including gravidity, parity, height, smoking, weight, body mass index (BMI) or weight gain over the course of pregnancy, or in fetal or neonatal growth parameters between non-asthmatic women and women with mild or moderate/severe asthma. Moderate/severe asthmatics were found to have a reduced dietary consumption of energy, total, saturated, polyunsaturated and monounsaturated fats, carbohydrates, thiamine, riboflavin and magnesium. Maternal circulating fatty acids and antioxidants increased as pregnancy progressed in each group, but unexpectedly, higher maternal circulating levels of omega (n3) fatty acids were found in moderate/severe asthmatics at the end of pregnancy (G36), and were inversely associated with fetal/neonatal head growth. Since there were no growth restricted neonates found in this cohort, it seems that placental transfer of n3 PUFA may be compromised in asthmatic pregnancies. Due to the study protocol, the asthmatic women had well controlled asthma, this is possibly why no growth restricted neonates were found in this cohort. There were no significant differences found in maternal circulating levels of fatty acids or tocopherols in wome who were using ICS or who were cigarette smokers; however, smokers tended to have reduced levels of carotenoids. High levels of n3 fatty acids and antioxidants were found in moderate/severe asthmatics, suggesting there is a maternally mediated compensatory mechanism to protect the fetus during pregnancy from asthma induced inflammation and oxidative stress during pregnancy. Therefore, the maternal circulating fatty acid and antioxidant profile is altered in women with moderate/severe asthma in response to the increased inflammation and oxidative load. Fatty acid levels were inversely associated with fetal growth in the presence of adequate asthma control, adequate diet and low antioxidant levels, whereas antioxidant levels were generally positively associated with, and may protect fetal growth, suggesting that factors other than asthma severity and diet may influence fetal growth, including inadequate transfer of fatty acids to the fetus. From a clinical perspective, women with moderate/severe asthma should be vigilant in controlling their asthma throughout pregnancy, since controlling the inflammation and subsequent oxidative stress will enable normal fetal growth within an adverse environment. Finally, in order to gain any benefit towards improving fetal growth, pregnant women with moderate/severe asthma should consider supplementation with antioxidants.Thesis (Ph.D.) -- University of Adelaide, School of Paediatrics and Reproductive Health, 201