Grand Rounds

What is the Recurrence Risk for Hyperemesis Gravidarum?

BACKGROUND AND PURPOSE:

Nurmi et al. ( AJOG 2018) studied the recurrence rate for hyperemesjs gravidarum (HG)

Analysis of Finnish healthcare registries
- ≥1 pregnancy ending in delivery following a pregnancy diagnosed with HG
- Index case: The first pregnancy with HG
Recurrence rate was calculated by comparing
- The number of hyperemetic pregnancies that followed the index pregnancy
- Total number of pregnancies that followed the index pregnancy
Additional associations between recurring HG were analyzed including
- Age | Parity | Prepregnancy BMI | Smoking | Marital and socioeconomic status | Domicile | Month of delivery | ART | Sex | Number of fetuses

544 pregnancies with HG | 1,723 pregnancies without HG
- Overall recurrence rate: 24%
Chronological distribution patterns in subsequent pregnancies
- 1 pregnancy after the index pregnancy: 25% HG recurrence
- >1 pregnancy after the index pregnancy: 11% HG recurrence in all subsequent pregnancies
- 22% had a HG diagnosis in ≥1 but not all subsequent pregnancies
Index pregnancy associations
- Parity of 2 vs parity of 1: Recurrence more common (adjusted odds ratio (OR) 1.33; P = .046)
- Overweight women: Recurrence less common (adjusted OR 0.58; P = .036)
- Smoking after the first trimester: Recurrence less common (adjusted OR; 0.27, P < .001)
Subsequent pregnancy associations: Recurrence less common (compared to non-smokers)
- Quitting smoking in the first trimester (adjusted OR, 0.32, P = .010)
- Smoking continued after the first trimester (adjusted OR, 0.38, P = .002)
Female sex of the fetus was associated with higher odds of recurring hyperemesis (adjusted OR, 1.29, P = .012)

HG recurrence is unpredictable but does not recur in majority of women, with a trend for decreasing risk with each new pregnancy
Smoking decreased risk of recurring HG, consistent with other findings
- Chemicals in smoke may reduce expression of placental proteins

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