Another puzzling aspect of pre-eclampsia is the role of the father. Pre-eclampsia is more common in first pregnancies. One study showed that as long as the woman stays with the same partner, rates can drop dramatically (from 11.9 per cent to 4.7 per cent). However, when the woman changes partners for her second baby, the rate of pre-eclampsia rises to a whopping 24 per cent. Researchers further discovered that a shorter duration of cohabitation with the new partner placed the woman at greater risk (Lancet, 1994; 344: 973-75).
The authors could not explain their findings fully, but hinted at pre-eclampsia being linked to an immune response. In the study, they controlled for age, race, education, marital status and number of pregnancies and concluded that pre-eclampsia may be a disease of primipaternity (first fatherhood) rather than primigravidity (first pregnancy). The authors suggested that repeated exposure to the same sperm (immunological intercourse) can help strengthen a woman's immune system in much the same way as a vaccine is supposed to.What they did not do, however, was look into the lifestyles and stress levels of the second time married women. In second families, budgets may be tighter and stress levels higher, with the possibility of step children and more pressure than usual to make the situation work.
Had the authors studied the women's incomes and diets, their findings might have provided a better explanation than the editorial which accompanied the paper, which simply informed women that "monogamy does you good".