Contact: Ivy Pike, (614) 292-2766
Written by Jeff Grabmeier, (614) 292-8457Grabmeier.1osu.edu
STUDY OF AFRICAN WOMEN SUGGESTS MORNING SICKNESS CAN BE HARMFUL
COLUMBUS, Ohio - New research in Africa raises questions about the hypothesis that morning sickness serves a beneficial function in protecting a developing fetus.
The study among the Turkana people of Kenya found that women with morning sickness were more than twice as likely to have their fetus or newborn baby die, compared to pregnant women who did not have regular nausea and vomiting.
These results challenge a hypothesis - and limited research evidence -- that suggest morning sickness actually helps the developing baby by discouraging women from eating foods containing chemicals that might harm a fetus.
Most studies that have found benefits to nausea and vomiting in early pregnancy have been conducted in the United States or other Western countries where pregnant women have access to proper nutrition, said Ivy Pike, author of the new study and assistant professor of anthropology at Ohio State University. If women in developing countries are unable to eat normally because of nausea and vomiting, they may not be able to provide proper nutrition for their fetus.
"We have had so little information from women in developing countries where proper nutrition is not always readily available," Pike said. "This study suggests that the nutritional costs incurred as a result of nausea and vomiting in pregnancy may have negative consequences for women and their babies later on."
The study was published in the current issue of the journal Human Nature.
Pike gathered data during a 13-month field study in 1993 and 1994 among the Turkana, who are nomadic livestock herders who live in a region of Kenya that receives limited rainfall and often experiences drought. As a result, there is often seasonal variation in the amount and types of food that are available.
Pike was able to follow 68 women who were pregnant at some point during the field study. She conducted interviews and did a variety of health tests during the course of the pregnancies.
Results showed 44 percent of the pregnant women reported akitumitum, the Turkana word for morning sickness. These women showed a number of disadvantages compared to women who didn't experience morning sickness, Pike found. For example, women who had morning sickness scored lower on tests of body fat than did other women during the second and third trimesters - suggesting that they were not putting on needed weight. This was especially true among older pregnant women.
The results also showed that women who suffered from morning sickness were 2.34 times more likely to have their pregnancy end spontaneously or have their child die within a few days of birth.
"For this small sample of Turkana women, the results suggest that marginally nourished pregnant women experienced additional nutritional stress if they experienced nausea and vomiting - and this is linked to negative outcomes to their pregnancy," Pike said.
Pike cautions that the results of this small study don't discount the possibility that morning sickness is indeed an adaptation that evolved for the benefit of pregnant women and their babies. However, the results suggest the hypothesis must be examined much more closely, and in a variety of populations, before it is accepted.
For example, if morning sickness is an evolutionary adaptation, it would have evolved in ancient peoples who lived much more like the Turkana than like present industrialized societies. "If pregnancy sickness is a natural adaptation, the Turkana women and others who live with limited nutritional resources pay a steep price," she said.
Proponents of the theory that morning sickness is protective note that it occurs mainly during the first 20 weeks of pregnancy, when organ development is occurring and the fetus is most vulnerable to harmful chemicals. However, Pike noted that morning sickness actually put the fetuses of Turkana women in more danger later on during pregnancy.
"It is difficult to imagine the circumstances under which maintaining a pregnancy during the first 20 weeks, only to be at greater risk for pregnancy loss in the second half of pregnancy, is advantageous," she said.
The study was supported with grants from the National Science Foundation, The Population Council, and the Wenner-Gren Foundation.
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