You've introduced your baby to solids, and he loves 'em. But sometimes what goes in doesn't come right out, making him (and you!) miserable. You're not alone. First foods are often rough on a digestive system that's used to only breast milk or formula.

The hard-to-miss signs your baby's constipated: He's cranky and crying, and draws his legs up when he passes stools, which are hard, compact, and sometimes large. He may even start to resist pooping because it's so painful. But withholding stools will only make him more backed up as time goes on, so it's important to solve the problem before you start potty training. An over-the-counter suppository to soften poop can help, but first try these simple changes, suggests Anthony Olivà, M.D., a pediatric gastroenterologist at Texas Children's Hospital in Houston:

Feed him more fiber-rich and laxative foods, like one jar of peas, beans, apricots, prunes, peaches, or pears a day. If he's already eating finger foods, offer Cheerios or small cubes of apple, fig, or peach. (For now, limit bananas, rice cereal, and cheese, which can be binding.)

Increase fluids. It'll help move the fiber through his system. Start with more breast milk or formula; now that he's on solids, he can have two to four ounces of water a day, too. If he's still having a problem after a couple of days, try the same amount of water-diluted juice (apple, pear, prune).

Get physical. Doctors aren't sure why movement helps, but it does. Bicycle his legs while he's on his back, and if he's ready for it, give him more space and time to crawl, cruise, or walk.