What to Expect the First Year: (Updated in 2025)

by Heidi Murkoff

Clearly, the first is a very big year for those so little. Take growth, with a typical doubling of birth weight in the first 20 weeks and a tripling of birth weight by the first birthday. Length (or height, by the time your child is standing at a year) has increased by perhaps 50 percent, and brain growth (as roughly measured by head circumference) has increased by 30 percent.

For brain development, the first 3 years are most important, but the first 12 months are critical.

evidence that breastfed babies may be less likely to develop asthma and eczema than babies fed formula.

breast milk is actually ingeniously calorie controlled. The lower-calorie foremilk (served up at the start of a feed) is designed as a thirst quencher. The higher calorie hindmilk (served up at the end of a feed) is a filler-upper, signaling to a nurser that it’s quitting time.

Studies show that former breastfeeders are less likely to battle weight as teens—and the longer they were breastfed, the lower their risk of becoming overweight.

Speedier postpartum recovery. It’s only natural that breastfeeding is best for newly delivered moms, too—after all, it’s the natural conclusion to pregnancy and childbirth. It’ll help your uterus shrink back to prepregnancy size more quickly, which in turn will reduce your flow of lochia (the postpartum discharge), decreasing blood loss. And by burning upward of 500 extra calories a day, breastfeeding your little one can help you shed those leftover pregnancy pounds faster.

For now, consider buying 5 to 10 undershirts (newborn size) and 7 to 10 onesies.

Consider buying around 7 footed stretchies.

Stock up with four 4-ounce bottles and ten to twelve 8-ounce bottles. If you’re combining bottle-feeding with breastfeeding, four to six 8-ounce bottles should be plenty. If you’re nursing exclusively, one 8-ounce bottle is enough as a just-in-case.

Happiness, as you’ll soon discover, is a warm baby.

too much swing time, especially as your baby gets older, isn’t great for motor development since it limits the time baby spends flexing his or her muscles.