Haugen et al [18] set out to
examine the risk of pre-eclampsia and other adverse
pregnancy outcomes for women who fell outside these
limits. For nulliparous women, the odds ratio for preeclampsia
was 2.44 (95% CI: 2.03-2.92) for women
who had gained more weight than recommended. For
parous women, the corresponding odds ratio was 2.19
(95% CI: 1.62-2.96). When weight gain in pregnancy
is associated with an outcome such as pre-eclampsia,
reverse causation must be considered, since edema, a
common consequence of pre-eclampsia, will cause
increase in weight.