Having another baby may not be at the top of your to-do list just yet, but when you're ready, plan to give yourself plenty of time, recommends Serena Chen, M.D., of the Institute for Reproductive Medicine and Science at Saint Barnabas Medical Center in Livingston, New Jersey. Many couples confront secondary infertility -- the inability to conceive again after having your first child.

Why it happens A big reason is age. "You and your eggs, plus your partner and his sperm, are older than the first time around," says Dr. Chen. Conditions such as endometriosis and fibroids, which crop up or worsen as you get older, or complications from your first pregnancy -- namely, scar tissue from childbirth or a dilation and curettage (D&C) -- are all risk factors for infertility.

When to be concerned If you're under 35 and haven't conceived after a year of unprotected sex, or you're over 35 and not pregnant after six months. Calculate carefully. "Most couples underestimate the length of time they've been trying," says Dr. Chen. Meanwhile, enjoy being the mom of one.

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