Second trimester HG demands vigilance

Women who experience hyperemesis gravidarum (HG) during the second trimester have an increased risk for certain birth complications associated with placental abruption, study results show.

Researchers found that women hospitalized for HG during the second trimester had a greater risk for developing preterm pre-eclampsia, placental abruption, and having a small for gestational age (SGA) birth than women who did not develop HG in pregnancy.

"The results indicated that pregnancies with hyperemesis gravidarum in the second trimester demand an increased alertness and supervision during the pregnancy for development of any adverse outcomes with abnormal placentation," said author Marie Bolin (Uppsala University, Sweden) in a press statement.

The authors, reporting in BJOG, used data from 1,155,033 births recorded in the Swedish Medical Birth Register between 1997 and 2009. In all, 12,270 (1.1%) of women experienced HG before the third trimester, with 10,186 of these cases first occurring in the first trimester.

Compared with pregnancies without HG, women with HG in either trimester had slightly increased risks for pre-eclampsia (36%) and SGA birth (18%), and a nearly 50% increased risk for placental abruption.

However, stratified by trimester, women with second trimester HG had a 2.1-fold increased odds for preterm pre-eclampsia compared with women without HG (1.4% to 0.6% respectively).

These women also had a 3.1-fold increased odds for placental abruption (1.1 vs 0.4%), and a 1.39-fold increased odds for SGA birth (4.0 vs 2.4%).

In contrast, women presenting with HG in the first trimester did not exhibit a significantly heightened risk for these complications.

Both HG and abnormal placentation are associated with high levels of human chorionic gonadotrophin (hCG), explain the authors. They say this could explain their findings, with high levels of hCG in the second trimester secondary to abnormal placenta development.

While physicians should be alert to abnormal placentation in women with second trimester HG, further research will be needed to clarify which preventive treatments are best, the authors conclude.

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