Nausea and vomiting in pregnancy, maternal nutrition and pregnancy outcome.

Nausea and vomiting in pregnancy (NVP), which is known to affect nearly 70% of all pregnant women, has been associated with favourable pregnancy outcomes such as decreased risk of miscarriage, low birth weight and premature delivery. The aim of this research was to determine the mechanism by which these protective effects of NVP may be brought about. Women suffering from NVP may decrease their intake due to the symptoms, may increase their intake to alleviate symptoms, or may change the quality of their diet. Both a retrospective questionnaire survey (n=201) and a prospective cohort study (n=52)were carried out between April 1999 and August 2001. Women were recruited mainly from two GP clinics in Guildford. It was found from both studies that the prevalence of NVP in the Guildford area is similar to that reported in other studies. Although this study found no relationship between NVP and birth weight and gestational age, women with NVP had higher cord IGF-1 levels compared to women without NVP (p=0.044). In addition, duration of NVP was inversely related to birthweight to placental ratio (p=0.011). Forty three women provided complete dietary information. It was found that energy intakes did not differ between women who had NVP compared with women who had no NVP, however the quality of diet varied between women with NVP and those without NVP. This is probably due to the fact that women with NVP had a high risk of cravings and aversions in pregnancy, leading to the difference in intake of certain nutrients such as riboflavin, calcium, zinc and copper. The strong association between NVP and aversions in pregnancy (P= 0.026) found in the retrospective study could lend further support to the "Embryo protection" hypothesis, which states that NVP is a protective mechanism, which has evolved to prevent the mother from the ingestion of foods that could be harmful to the fetus. Further studies using larger sample sizes, covering a range of socio-economic status and different regions are needed before definite conclusions can be drawn