If you find yourself wanting to keep everyone at arm's length during your third trimester, it's likely more than just your pregnancy nerves. A new study shows that women's "safety bubbles" actually expand during those final weeks of pregnancy.

The study, conducted in Cambridge at Anglia Ruskin University and the department of obstetrics and gynecology at Addenbrooke's Hospital, examined women's "peripersonal space" at all stages of pregnancy and compared it to non-pregnant women. Peripersonal space, often described as being within arm's length of another person, was found to increase as mom's baby bump grew, meaning that the further along women get, the more their brains became aware of who and what she allows to get close to her.

It's a fascinating find that gives insight into just what happens to a woman's brain as her baby grows inside of her. The first-of-its-kind study used audio-tactile tests, measuring pregnant women at three stages—in the second trimester (around the 20th week of pregnancy), in the third (around the 34th week) and about eight weeks postpartum—in addition to a group of non-pregnant women. The women, ages 21-43, experienced tapping sensations on their abdomens while being exposed to noises from loudspeakers.

What was most interesting was that the women did not seem to have quite as strong a reaction at 20 weeks or eight weeks postpartum as they did at the 34-week mark. "Our results suggest that when the body undergoes significantly large changes, at the stage when the abdomen is clearly expanded, the maternal brain also begins to make adjustments to the space immediately surrounding the body," Dr. Flavia Cardini, Senior Lecturer in Psychology at Anglia Ruskin University, said.

The researchers believe that the reaction is all part of a woman's instinct to protect her "vulnerable abdomen during the mother's daily interactions."

"Peripersonal space is considered a 'safety bubble' and it's possible that the observed expansion of this at the late stage of pregnancy might be aimed at protecting the vulnerable abdomen during the mother's daily interactions," Cardini said. "So as the mother's bump grows, in effect, the expanded peripersonal space is the brain's way of ensuring danger is kept at arm's length."

It makes sense considering a mother's natural instinct to protect her baby. For so many moms, this begins long before you hold your baby and truly deepens once we begin to consistently feel our little ones move and watch our bumps grow with every passing day.

As Colleen Temple wrote for Motherly, "Do you ever wonder why pregnancy and birth are not easy? Why these experiences can be raw and agonizing and challenging? Well, because motherhood can be raw and agonizing and challenging. Pregnancy and birth are just doing us a solid. They're prepping us for the next chapter we're about to enter—the chapter of becoming a mother."

The study also speaks to the amazing mind and body connection that happens during pregnancy. For expectant moms, as our baby grows, so too does our instinctual motherly urge. "Pregnancy involves massive and rapid changes to the body both externally, as the body suddenly changes shape, and internally, while the fetus is growing," Cardini said.

So don't feel bad about wanting to keep a little distance as you navigate your new pregnant body. It's just simple biology.

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