Timing is Everything When Having Babies

"Oops" she did it again... Reportedly.

Singer Britney Spears isn't confirming anything, but tabloids and bloggers say she's expecting her second child in October.

If that is the case, then that means she conceived just six months after little Sean Preston was born.

Perhaps Britney should have waited a little longer, according to a new study published in The Journal of the American Medical Association.

It says ideally, there should be more than 18 months between the birth of baby number one and the conception of number two.

Dr. Donn Slovachek says if you space pregnancies a little too close, mom doesn't have time to get back her stores, particularly if she's breast feeding.

He says she's going to be calcium and iron deficient, and you need some time to get that back.

In addition, the ligaments during pregnancy all loosen up and that takes time to tighten back up, so 18 months is probably a reasonable recommendation.

For each month under that, the study showed the risk of premature birth went up 1.9 percent. Low birth weight increased 3.3 percent.

Dr. Slovachek says if mommies have children close together, they will need to be sure to replace the vitamins and minerals babies use up by taking supplements, but those willing to wait for their bodies to replenish them naturally shouldn't wait too long.

The study recommends having babies less than five years apart. After that, infants have a 20 to 43 percent greater risk of being born too soon or too tiny, which is likely the result of a diminishing reproductive capacity as mom ages.

The March of Dimes says 12 percent of babies are born prematurely in the U.S., and nearly 8 percent are too small.

The organization is working to cut those numbers down to almost half by 2010.