Severe morning sickness in the middle stage of pregnancy is linked to problems with the placenta, say researchers.
They focused on a condition called hyperemesis gravidarum – severe illness or vomiting – which affects 0.5 to 3% of pregnancies, and is thought to be caused by high levels of human chorionic gonadotrophin. It often causes the mother to lose more than 5% of her body weight and requires intravenous fluids.
Dr Marie Bolin and colleagues at Uppsala University, Sweden, used figures from the Swedish Medical Birth Register between 1997 and 2009, looking at women admitted to hospital for hyperemesis gravidarum. Overall, 1.1% of the 1,155,033 women on the register had hyperemesis gravidarum before 22 weeks gestation.
Pregnancies with hyperemesis gravidarum in the first 12 weeks showed a slightly increased risk of pre-eclampsia, but no significant associations with placental abruption (the premature separation of the placenta) and small for gestational age babies.
But greater risks were seen in pregnancies with hyperemesis gravidarum in the second trimester (12 to 22 weeks). Compared with unaffected pregnancies, there was twice the risk of preterm pre-eclampsia, three times the risk of placental abruption, and a 39% raised risk of a small for gestational age baby.
The risk of stillbirth was not raised with hyperemesis gravidarum at any stage of pregnancy. Details are published today (30 January) in BJOG: An International Journal of Obstetrics and Gynaecology.
Dr Bolin said: "The results indicate that pregnancies with hyperemesis gravidarum in the second trimester demand an increased alertness and supervision during the pregnancy for development of any adverse outcomes associated with abnormal placentation.
"Further research is needed to consider the best treatment and techniques for surveying blood pressure and foetal growth in these high risk women."
Bolin, M.et al. Hyperemesis gravidarum and risks of placental dysfunction disorders: a population-based study. BJOG 30 January 2013 doi:10.1111/1471-0528.12132
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