The record-low temperatures and heavy snows of the polar vortex that whacked Pittsburgh the past winter have left a legacy: a little boomlet of aptly named "polar vortex babies" that are expected to be born from August to late September.

"With the polar vortex, people were staying in; it was too cold to go anywhere or do anything, so you stay in and keep yourselves busy. It's hibernation, and it's partly entertainment," said David Logan, an obstetrician/gynecologist with the Allegheny Health Network and director of obstetrics at Jefferson Regional Medical Center, Jefferson Hills. "If you can't get out, maybe you can't go get the form of contraception you normally use."

West Penn and Forbes Regional hospitals, which together average 3,500 births annually, are experiencing respective increases of 27.8 percent and 15.9 greater than their average number of deliveries each summer. The surge is partly due to the anticipated influx of "polar vortex" births, doctors said.

Other local hospitals also expect to feel the whiplash of winter in the delivery room.

"The anticipated 'polar vortex' births will definitely make delivery time exceptionally busy," said Maribeth McLaughlin, chief nursing officer and vice president of Patient Care Services at Magee-Womens Hospital of UPMC in Oakland. The region's largest maternity ward, Magee has had 11,000 births in the past year.

The looming increase in births mirrors a national trend, with August being the most popular birth month in 2012 and 2013, according to the Centers for Disease Control and Prevention. A spokeswoman for Magee also said the hospital typically sees more births in the summer season compared to the winter months but is expecting more this year.

Jumps in birth rates have been historically linked to conditions that drive people indoors.

"A textbook example is the New York blackouts," said Dr. Logan, "People wanted to stay inside at night, be close with their partners, and nine months later there was a spike in birth rate."

Micro spikes in birth rates can even occur after a regular winter, Logan said.

"People aren't in the mood to do anything but be together inside."

However, he was careful to note that there are "all kinds of interesting things that play a role into when someone wants to have a baby. Some women love the spring, so they can get outside right away with a stroller, or some might look at when would be best for their job."

One facet that many mothers might now want to consider is how the birth season can affect personality.

"In the mid of winter, it's dark by 4 or 5 o'clock," said Logan. "These seasonal changes play a huge role in humans' mental states."

Research has correlated fall births with an increased risk in developing food allergies, pointing to decreased UV light exposure as a potential explanation. A study published in Nature Neuroscience has suggested that exposure to daylight can affect biological clocks, explaining why winter-born babies might be more susceptible to developing mental disorders such as schizophrenia, depression and seasonal affective disorder.

Regardless of the season, every birth is its own "dream come true," according to Courtney Cassat, 29, of Cranberry, who just delivered on Friday at West Penn. "It's only been a few hours, and we are just getting to know him. We're so excited for what the future holds."