Childhood obesity is on the rise and is a major risk factor for type 2 diabetes later in life. Recent evidence indicates that abnormalities that increase risk for diabetes may be initiated early in infancy. Since the offspring of women with diabetes have an increased long-term risk for obesity and type 2 diabetes, the impact of maternal metabolic abnormalities on early nutrition and infant metabolic trajectories is of considerable interest. The purpose of the study is to investigate the impact of maternal nutrition and metabolic abnormalities in pregnancy on human milk and subsequently on infant health over the first year of life.

The current investigation is a prospective study conducted within ongoing cohort studies of women and their offspring. Pregnant women attending outpatient obstetrics clinics in Toronto, Canada are recruited. The overall study protocol includes four study visits between the second half of pregnancy and the first year of infant's life and interim phone call interviews:

• Pregnant women undergo an oral glucose tolerance test at an expected average of 30 weeks of gestation and complete medical and lifestyle questionnaires including food frequency questionnaires.
• Infant birth anthropometry measurements and human milk samples are collected at an expected average of 3 days postpartum. The timing of onset of lactogenesis II is asked at 3d, 5d, 7d postpartum or until the event occurrence up to day 7.
• At 3 months postpartum, follow-up assessments including infant anthropometry, medical and lifestyle questionnaires and human milk sample collection are completed.
• Interim telephone interviews are conducted at 6 weeks and 5, 7, 9 months postpartum to characterize infant feeding and supplementation behaviors.
• At 12 months postpartum, infant anthropometric assessments are conducted.

Inclusion Criteria:

• singleton or twin pregnancy
• aged 20 years or older at the time of recruitment
• intention to breastfeed

Exclusion Criteria:

• pre-existing diabetes

Pregnant women are recruited in outpatient clinic waiting areas at Mount Sinai Hospital in Toronto, Canada, a large tertiary care centre.