Pregnancy Nesting: Evolutionary Behavior or Just an Old Wives’ Tale?

According to the American Pregnancy Association (APA), nesting is a strong, sometimes overwhelming, urge to clean and organize your environment before your baby arrives. It does not affect all women, but it does affect many women late in the third trimester. An old wives’ tale says nesting is a natural instinct to prepare for birth, and that it signals the beginning of labor.

The part about labor following nesting is probably just an old wives’ tale, but a surge in energy and a strong desire to prepare for your baby late in pregnancy is not irrational and is supported by the experience of many women, and by some scientific research. A study from the Department of Psychology, Neuroscience and Behavior at McMaster University in Canada followed a large group of pregnant women through their pregnancy and compared pregnant women to non-pregnant women to learn more about nesting. The study used questionnaires and interviews conducted by midwives.

The study is published in the  journal Evolution & Human Behavior. The researchers proposed that nesting behavior in other animals is well documented. It is instinctive for animals to select, build, and protect their nest before giving birth. They wanted to see if the same instinct occurred in humans. Their conclusion from the study was that nesting behaviors in pregnant women  do include a predictable burst of energy in the third trimester and a compulsion to prepare and protect their environment. Part of the protection instinct included limiting social contacts to people that were trusted friends and family members.

Surprisingly, the powerful motivation and energy to nest occurs during the third trimester, when most women describe having felt most tired. The authors of the study conclude that nesting is not a frivolous activity and it serves the same basic purpose for humans as it does for other animals.

Nurture Versus Nature 

How much of nesting is evolutionary and instinctual versus common sense and practical is debatable. It is probably a bit of both. Nesting behaviors include cleaning, organizing, stocking, and packing for a trip to the hospital. The burst of energy to get this done may come from the end of a long boring pregnancy, the realization that time is getting close, and the excitement that the event is finally near, says APA.

On the other hand, some research suggests that a surge in estrogen late in pregnancy is a programmed energy boost to help a mother prepare and protect the home (or nest) before birthing. It may also be nature’s way of helping mothers prepare to bond and attach to a new baby. In any case, whether nature or nurture, nesting serves its purpose.

Nesting is something many women look forward to and enjoy. It is part of the excitement of a new and wonderful part of life. The only thing to keep in mind is not to get carried away with the urge to nest. Avoid obsessing with nesting to the point where it interferes with sleep or causes anxiety. Avoid lifting heavy objects or moving heavy furniture. Watch out for strong cleaning products in poorly ventilated spaces. Other than that, think of nesting as an urge or instinct you share with all mothers throughout history. Nesting provides a safe environment for babies and ties humans to their ancestral past.

Christopher Iliades
Dr. Chris Iliades is a medical doctor with 20 years of experience in clinical medicine and clinical research. Chris has been a full time medical writer and journalist since 2004. His byline appears in over 1,000 articles online including EverydayHealth, The Clinical Advisor, and Healthgrades. He has also written for print media including Cruising World Magazine, MD News, and The Johns Hopkins Children's Center Magazine. Chris lives with his wife and close to his three children and four grandchildren in the Boston area.

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