Morning Sickness in early pregnancy linked to lower risk of miscarriages and still births.

Nausea and vomiting in early pregnancy affects 50-80% of pregnant women. Researchers have linked its etiology to imbalance in carbohydrate metabolism, rising hormonal levels in pregnancy, psychosomatic factors  evolutionary survival adaptation which protects pregnant mothers and their babies from food poisoning. 

 Few  observational studies in the past have documented that incidence of pregnancy loss is lower in patients who have morning sickness in first trimester.

A new study published in the in the journal JAMA Internal Medicine[1] found that women who suffer from nausea and vomiting in the first trimester have 50% less chance of miscarriage.

The study is a result of secondary data analysis of a Randomized Control Trial (RCT) examining Effects of Aspirin in Gestation and Reproduction (EAGeR) Trial.[2] The EAGeR study is a multi-site, double-blinded randomized trial designed to assess the effects of low-dose aspirin on implantation and pregnancy outcome carried out by researchers at NIH's Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD) and other institutions.

The secondary analysis was limited to women who had a pregnancy confirmed by positive human chorionic gonadotropin (hCG) test, had a history of at least one pregnancy loss. A total of 797 study subjects was recruited. The women kept a daily diary for nausea and vomiting from week 2 to week 8 of pregnancy, and monthly thereafter.

Out of 797 pregnancies, 188 ended in loss (23.6%), and at the end of 8 weeks about 57.3 percent of the women reported experiencing nausea and 26.6 percent reported nausea with vomiting. 

In this cohort of women, it was seen that nausea alone or nausea with vomiting during pregnancy were associated with nearly 50%-75% reduction in the risk for pregnancy loss. When the analysis was done for peri-implantation pregnancy loss, the results were similar but they were not statistically significant.

Younger women (age <25 years) suffered much more with nausea and vomiting as compared to older women.

The association persisted even after accounting for confounding factors like maternal stress, alcohol intake, caffeine intake, smoking, fetal sex, multiple-fetal gestation, and karyotype.

Stefanie Hinkle, the lead author and a researcher at the national institute said "Our study evaluates symptoms from the earliest weeks of pregnancy, immediately after conception, and confirms that there is a protective association between nausea and vomiting and a lower risk of pregnancy loss.” But, was not sure whether the study results could be applied to primigravida.

She also went to stress that women with no nausea or vomiting should not be alarmed as a result of this study. "Every pregnancy is different and just because they don't have symptoms doesn't mean they're going to have a pregnancy loss," Hinkle said.[3]

The study was also followed by an accompanying editorial by Siripanth Nippita, MD, and Laura E. Dodge, ScD, MPH, from the Department of Obstetrics and Gynecology, Beth Israel Deaconess Medical Center. They said "This study's contribution to the existing literature is valuable for several reasons. It builds on a prior cohort study by Sapra et al and similarly enrolled a large sample of women before conception."

They further quote “The widespread availability of sensitive urine hCG tests coupled with real-time electronic data capture using mobile phone apps or similar technology has the potential to improve data quality and eliminate recall bias. Given these methodologic advantages over previous investigations, we hope that such studies can further deepen our understanding of the underlying causes of [nausea and vomiting in pregnancy]."

The researchers also urged women with nausea and vomiting in pregnancy to seek medical consultation since it negatively affects the quality of life.

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[1] http://archinte.jamanetwork.com/article.aspx?articleid=2553283

[2] http://grantome.com/grant/NIH/ZIA-HD008795-08

[3] Stefanie N. Hinkle, Sunni L. Mumford, Katherine L. Grantz, Robert M. Silver, Emily M. Mitchell, Lindsey A. Sjaarda, Rose G. Radin, Neil J. Perkins, Noya Galai, Enrique F. Schisterman. Association of Nausea and Vomiting During Pregnancy With Pregnancy Loss. JAMA Internal Medicine, 2016; DOI: 10.1001/jamainternmed.2016.5641