PORTLAND, Ore. -- For expectant mothers, this week's kind of heat is extremely uncomfortable and can be dangerous.

"It's really hard right now, it's harder to walk around because I'm nine months right now," said Yana of Portland, hanging out with her kids at Jamison Square in the Pearl District.

"My fingers, I still don't wear my wedding ring because my fingers get really hot and sweaty," said Sarah Godding of Portland, who remembers being very pregnant last summer.

Dr. Lishiana Shaffer, an OB/GYN at OHSU is hearing about the heat from her patients. "It is so hot, everyone is totally swollen!" She says hot weather is hardest on women in their third trimester. She advises women to wear looser, open toed shoes like flip flops because of foot swelling, and take off restrictive jewelry like rings to let your hands breath.

The number one risk? Not drinking enough water, and having too much caffeine, which can make you dehydrated.

"Dehydration can lead to pre-term labor or at least pre-term contractions, which can be worrisome," Dr. Shaffer cautioned.

Foot, leg and hand swelling gets a lot worse in triple digits too. If you're at work, put your feet up under your desk.

If you're chasing kids around, stop to take a break in the shade. In extreme cases, Dr Shaffer says heat can affect your blood pressure and slow your baby's movement.

"But you'll have symptoms before, you're going to feel short of breath, you'll feel your heart racing first and those are times to slow down and take it easy."

Another tip, hold off on exercising this week if you're pregnant. Your body temperature is already running hotter than normal, so you can overheat easily.

And if water is getting boring, orange juice, sports drinks with electrolytes or milk are good replacements.