New risks for pre-eclampsia

Miscarriage and infertility drugs link to pre-eclampsia

A European study including more than 20,000 first-time moms-to-be has found that while those who have never miscarried and didn’t have problems getting pregnant had a 5.2 % risk of pre-eclampsia, the risk shot up to 50% among women who’d had three or more miscarriages (women who’d one or two miscarriages were not found to be at higher risk).

Among women who’d both miscarriages and treatment for infertility, the risk for pre-eclampsia was 13% and the study also revealed that women who had infertility treatment had a 25% higher risk of pre-eclampsia. Women who became pregnant after hormone treatment to stimulate ovulation had a doubled risk of pre-eclampsia compared to women without treatment. Assisted conception treatment (sich as IVF) was not linked to an increased risk, even though hormone stimulation is part of the procedure.

Different causes of infertility (for example, polycystic ovary syndrome, blocked fallopian tubes) can likey explain the difference in risk for pre-eclampsia. It’s likely that factors in mothers that cause infertility may also give an increased risk of pre-eclampsia. It’s less likely that the treatment itself explains the increased risk, even if this cannot be excluded.

The causes of pre-eclampsia are unknown, but involve the placenta. The placenta is vital for normal development of the pregnancy—failure in its development and function seem to be an important mechanism in the development of pre-eclampsia but no-one knows why. The results from this study show that the protective effect seen after earlier normal pregnancies (births or terminations) isn’t present among women with repeated miscarriages. The study indicates that common causal factors linked to the placenta's development and function may be present in infertility, repeated miscarriages and pre-eclampsia.

Facts about pre-eclampsia

• It affects 3-5 % of all pregnant women.
• The greatest risk is among first-time mothers.
• it develops in the second half of pregnancy
• It’s recognized by high blood pressure and protein in mother’s urine.
• In mild cases the mother can be unaffected by the condition, but in serious cases, pre-eclampsia can be life-threatening for mother and baby, with organ failure and danger of seizures among mothers.
• The child risks poor growth and development due to insufficient placenta function.
• The only treatment is delivery of baby and placenta.
• Pre-eclampsia is a major cause of premature birth.

Among women who have given birth earlier, the risk is approximately halved. The same applies to women who have had earlier terminations. It’s unknown why earlier normal pregnancies protect against pre-eclampsia in later pregnancies.

The study is published in the January 2009 issue of the British Journal of Obstetrics and Gynaecology.

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