5 Months Old. Baby should double her newborn weight by this month. Ask your doctor what height and weight percentile she’s in at her checkup to make sure she’s on track. If Baby is at risk for being underweight, find out what you can do to help her gain more.
http://www.parents.com/baby/development/growth/baby-weight-gain/
I cannot recall seeing a baby for whom slow weight gain in the first 2 to 6 weeks was the only sign of a problem. Older babies, 2 to 12 months of age, grow at varying rates. Weight gain should not be used as a major criterion of good health.
http://drjaygordon.com/newborns/scales.html
Other factors should be considered when a full-term baby is gaining weight slowly: Doesn't gain about an ounce per day (30g/day) until 3 months of age. Doesn't gain about 0.67 ounces per day (20g/day) between 3 and 6 months of age. Doesn't regain birth weight by 10 to 14 days after birth. Has a dramatic drop in rate of growth (weight, length, or head circumference) from his or her previous curve.
http://www.hopkinsmedicine.org/healthlibrary/conditions/pregnancy_and_childbirth/slow_or_poor_infant_weight_gain_90,P02880/
Other factors should be considered when a full-term baby is gaining weight slowly: 1  Doesn't gain about an ounce per day (30g/day) until 3 months of age. 2  Doesn't gain about 0.67 ounces per day (20g/day) between 3 and 6 months of age. 3  Doesn't regain birth weight by 10 to 14 days after birth.
http://www.hopkinsmedicine.org/healthlibrary/conditions/pregnancy_and_childbirth/slow_or_poor_infant_weight_gain_90,P02880/
Big and small babies. Newborn Baby birth weight. At full term, the avarage baby will be about 20 inches (51 cm) long and will weigh approximately 6 to 9 pounds (2700 to 4000 grams).
http://www.baby2see.com/baby_birth_weight.html
‡ The average breastfed baby doubles birth weight by 3-4 months. By one year, the typical breastfed baby will weigh about 2 1/2 – 3 times birth weight. 1. Sources: World Health Organization Child Growth Standards, 2006. Available at: http://www.who.int/childgrowth/en/. To figure average weight gain, we used the weight-per-age percentile charts for birth – 5 years. The range is a combination of boys and girls 5% to 95%, rounded to the nearest 5 grams. Click here for more details on calculations [PDF file]. Riordan J. Breastfeeding and Human Lactation, 3rd ed.
http://kellymom.com/bf/normal/weight-gain-metric/
3 months old. At this stage, your baby will start to move away from a steady gain of about 6 ounces per week to a little less than 4 ounces. This means that she will gain roughly 2 pounds this month, and every month following until seven months old.
http://www.parents.com/baby/development/growth/baby-weight-gain/
Another common problem at early checkups is a baby that is not gaining what the practitioner considers to be “normal weight gain.” There is not general agreement on normal weight gain and the range in texts are from 4 to 8 ounces a week. Some babies are genetically destined to be a lot smaller or larger than others.
http://drjaygordon.com/newborns/scales.html
From now until Baby is 6 months old, she will likely grow an inch a month and gain 5-7 ounces a week. If feeding is going well, your baby will be steadily gaining weight. Baby Should Eat: Breast milk or formula.
http://www.parents.com/baby/development/growth/baby-weight-gain/
Consider these general guidelines for infant growth in the first year: 1  From birth to age 6 months, a baby may grow 1/2 to 1 inch (about 1.5 to 2.5 centimeters) a month and gain 5 to 7 ounces (about 140 to 200 grams) a week. Expect your baby to double his or her birth weight by about age 5 months. From ages 6 to 12 months, a baby may grow 3/8 inch (about 1 centimeter) a month and gain 3 to 5 ounces (about 85 to 140 grams) a week. Expect your baby to triple his or her birth weight by about age 1 year.
http://www.mayoclinic.org/healthy-lifestyle/infant-and-toddler-health/expert-answers/infant-growth/faq-20058037
typical weight gain for infant
The typical weight gain for infant is 5 to 7 ounces.