How The Placenta Responds to Famine

Lessons from the Dutch Hunger Winter

Journal: Placenta
Date: May 2011

Summary
During World War II, food supplies became increasingly scarce in The Netherlands as the nation plunged into an unusually harsh winter. Then, in November 1944, the Germans retaliated against the Dutch for a failed attempt to stop the transport of Nazi troops by rail. The Nazis blocked food and fuel supplies to western Holland, resulting in severe hunger and starvation for 4.5 million people. This is known as the Dutch Hunger Winter, or the Dutch Famine. Somewhere between 18,000 and 22,000 people died of starvation by the time food supplies were restored in May of 1945, when allies liberated The Netherlands. Many more were severely malnourished - including women who were pregnant, or about to become pregnant.   

Dutch medical professionals documented the course of women’s pregnancies with great detail, including mothers’ weight and blood pressure, the weight and size of babies and placentas at birth, the length of umbilical cords and written descriptions of labors and deliveries. The babies born from these mothers are known as the Dutch Hunger Winter cohort. Many studies have followed the famine’s effects on the health of the cohort throughout their lives. The subject of this research brief is how placentas responded to the famine during different stages of pregnancy.  

In a study entitled Effects of famine on placental size and efficiency, the authors collected data from the cohort birth records to gain a better understanding of how the placenta responds and adapts to famine.  
 
Key findings: 

  1. Overall, babies that were either conceived during the famine or who were already in utero, had smaller placentas, were shorter, thinner and had smaller head circumferences at birth than those born before the famine. The reduced placental size changed the ratio of baby weight per gram of placenta, which is considered the measure for placental efficiency – or how well it’s doing its job. Depending on the stage of pregnancy during the famine, the placenta became either more or less efficient as a result.

  1. In early pregnancy, the famine affected the way the placenta implanted into the womb, impairing the placenta’s ability to establish adequate blood vessels for nutrient and oxygen supplies to the fetus. In response, the placenta stayed small relative to the size of the fetus. This suggests the placenta adapted by becoming more efficient as a result of exposure to famine during the early stage of pregnancy.

  1. Babies that were in mid or late pregnancy during the famine were smaller at birth in relation to the size of the placenta, than babies born before the famine. This suggests that the placenta became less efficient as a result of exposure to famine during mid or late pregnancy.

  1. There were sex differences in placental response to the famine. Among boys, famine during early pregnancy resulted in smaller placental size and thickness, suggesting the implantation process was impaired. In girls, thickness increased during late pregnancy. The authors speculate that the increased thickness is an attempt to compensate for reduced growth, by burrowing deeper into the utero-placental arteries for more nutrients. 

  1. Women who lived through the famine and conceived a child afterward, also had reduced placental size and thickness, for up to 18 months post-famine (the end of the study period). Their placentas were also more oval shaped than those of babies born before the famine, suggesting implantation was impaired for some time after having been exposed to famine. The authors note this oval shape is similar to placentas from preeclamptic pregnancies – a disorder initiated by impaired implantation.   

Making sense of it
The placenta is one of the most important organs in the body. During pregnancy, it carries oxygen and nutrients to the fetus, provides immune system protections, secretes hormones and discards waste. It grows and functions in response to available nutrition, and changes size and shape depending on the mother’s nutritional status.  

We know that boys and girls differ in the way they grow in the womb. The findings from this study are consistent with the hypothesis that the growth of boys in the womb depends more on the immediate maternal diet than does the growth of girls. This is because boys grow as fast as possible over the course of pregnancy with as little placental tissue as possible, making them more vulnerable if their nutrition is compromised.  Girls are more influenced by maternal metabolism and make a larger investment in placental growth.  

Putting all of this into context with other information gathered from the Dutch Hunger Winter cohort, researchers are now able to better predict health outcomes of babies born from pregnancies with altered placental function as a result of nutritional deprivation. The findings of this study contribute to our understanding of placental health, maternal-newborn health and the long-term effects of nutrition. It demonstrates that the placenta is a key organ in the life of every individual, and clearly shows the need for a nutrient-rich diet for women during pregnancy.    

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The OHSU Bob and Charlee Moore Institute for Nutrition & Wellness supports human research that seeks to find the links between maternal stresses, including poor nutrition, and elevated disease risks for babies as they become adolescents and adults. 

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Roseboom TJ, Painter RC, de Rooij SR, van Abeelen AF, Veenendaal MV, Osmond C, Barker DJ. (2011). Effects of famine on placental size and efficiency. Placenta, 32(5):395-9. PMID: 21435715. Retrieved from https://doi.org/10.1016/j.placenta.2011.03.001