The Centers for Disease Control says the rate of twin births is up 76 percent over three decades. In many cases that's the result of fertility treatments.

The reason multiple births are a problem is that they come with increased risk of dangerous side effects to both the mother and the child.

“The new recommendations doctors are saying, if you’re under 35, we’re just going to put in one embryo and 35-40 … only up to two or three,” said CBS News chief medical correspondent Dr. Jon LaPook.

He said physicians did recognize that in vitro fertilization (IVF) treatments needed to change. 

Also this week there was new information about a controversial question; can you be overweight but still be healthy? An article published in the annals of internal medicine says the answer is no.

CBS News contributor Dr. Holly Phillips told that this was a very “interesting” study that looked at data from more than 60,000 patients.

 “It’s not just how you feel and whether or not you think you’re healthy,” she said. “It’s really about getting to a healthy number on the scale because there may be other things that can cause problems.”