Appendix D: Gaps in the evidence
PHIAC identified a number of gaps in the evidence relating to the interventions under examination, based on an assessment of the evidence. These gaps are set out below.
1. There is a lack of evidence on the underlying mechanisms linking gestational weight gain and pregnancy outcomes. This is needed to help determine whether weight management is safe and appropriate for pregnant women.
2. There is a lack of evidence on how much weight should be gained during pregnancy, when is the most effective time for women to start managing their weight after childbirth and the optimal rate of weight loss.
3. There are few well-designed UK intervention studies on weight management in pregnancy and after childbirth. In particular, there is a lack of evidence on safe, effective interventions for women who are obese but who do not have diabetes, and those who are breastfeeding.
4. There is a lack of evidence about the effectiveness and cost effectiveness of weight management interventions for women before pregnancy – including for those who may be planning a pregnancy.
5. There is limited evidence about the effectiveness and cost effectiveness of weight management interventions in pregnancy and after childbirth for women from disadvantaged, low-income and minority ethnic groups.
6. Few weight management interventions include adequate and validated measures of diet and physical activity. They often rely on self-reporting.
7. Few studies of weight management before, during and after pregnancy include interventions that are evaluated using process and qualitative data to determine which components are effective.
8. There is limited evidence on the role of breastfeeding in helping women to gain or retain a healthy weight after childbirth.
The Committee made 5 recommendations for research.