SWS: key findings

The SWS has a unique study design that facilitates the examination of women’s diets both before and during pregnancy as well as their offspring’s dietary intake.

An interesting finding from the SWS that takes advantage of the study design, is that women who become pregnant within three months of the initial interview were not more likely to comply with recommendations for planning a pregnancy compared to those who did not [134].

Although women who became pregnant reduced smoking, alcohol consumption and caffeinated drinks there was little change in their adherence to fruit and vegetable recommendations [135].

These findings suggest that more work on promoting dietary recommendations for women of childbearing is required.

One of the major pieces of work using these dietary data has been the identification of dietary patterns (DPs).

A consistent DP termed the ‘prudent’ DP was identified using principal component analysis (PCA) of the women’s FFQ data. This diet is high in fruit, vegetables, wholemeal bread, pasta, yoghurt and breakfast cereals and low in chips and roast potatoes, sugar, white bread, red and processed meat, full-fat dairy, crisps, cakes and biscuits and soft drinks [136].

Higher educational attainment was found to be the most important influence on adherence to the prudent DP [128].

In a subgroup of non-pregnant women, adherence to the prudent DP remained relatively stable over a two year period [122].

PCA was also applied to the children’s FFQ data at 6- and 12-months.

The main DP identified was one that is high in fruit, vegetables, and home-prepared foods (the ‘infant-guidelines’ DP).

The DPs at 6- and 12-months were correlated and a higher adherence to this DP was associated higher maternal educational attainment, lower maternal BMI, older mothers and those who are non-smokers and watch television less [129].

Children who adhered to this infant-guideline DP were also found to gain weight and skinfold thickness more rapidly from age 6- to 12-months [137] and have higher scores for full-scale and verbal IQ at age 4 years [138]. Maternal diet was a major influencer on adherence to a prudent DP at age 3 years [139].

There have been a number of validation studies using SWS data.

In papers comparing dietary data from FFQs among women and children with food diaries, estimated nutrient intakes were slightly higher from FFQs [125, 130, 132].

However, the ranking of individuals in quartiles according to estimated nutrient intakes was similar between FFQ and food diaries [125, 132].

Furthermore when compared to serum (in blood) vitamin C as a biomarker, the percentage of women classified into the correct quartile for intake was similar for the FFQ and food diaries [125].

The ‘prudent’ dietary pattern identified using PCA from FFQs and food diaries from women in early pregnancy in the Princess Anne Hospital study was similar, providing further evidence for the ability of the FFQs to accurately classify individuals according to their dietary pattern [140].

The FFQ data from the women were used to derive a shorter 20-item FFQ that has the ability to characterise a prudent dietary pattern which could potentially be used in future studies lacking time and resources and because it limits participant burden, making it easy to use among hard to reach groups [141].