Very low birth weight (VLBW) infants have more health and developmental problems than normal birth weight full-term infants. These problems are more common in males than female VLBW preterm infants. Male VLBW infants also experience less positive mother-infant interactions than females, especially when mothers are emotionally distressed. This is a significant problem because positive mother-infant interactions function as an important protective factor against the negative health and developmental outcomes associated with prematurity. The source of the vulnerability of male VLBW infants to health problems, suboptimal mother-infant interactions, and poor development goes beyond gender socialization differences and includes biological factors. Identification of infant and maternal biological markers/predictors of infant health and developmental outcomes could ultimately lead to interventions for VLBW preterm infants.

The purpose of this study is to confirm that testosterone rather than cortisol is a more reliable marker/predictor of complications affecting infants' health outcomes, mother-infant interactions, and infant cognitive/motor/language developmental outcomes; and that male infants exhibit a higher sensitivity to testosterone levels than female infants.

This longitudinal study will examine the associations of the steroid hormones, testosterone and cortisol, levels with infant health, mother-infant interactions, and infant cognitive/motor/language development ('infant development') in very low birthweight (VLBW, BW < 1,500 g) preterm (gestational age < 32 weeks gestation) infants after adjusting for maternal physical and mental health state, infant socioemotional and behavioral development, and characteristics of infants and mothers. Concurrent and repeated measurement of testosterone and cortisol levels both in infants and mothers will be conducted through infancy and early childhood (at birth, 40 weeks postmenstrual age, 12 and 24 months corrected age).

Inclusion Criteria:

• Neonates will be included if they are less than or equal to 32/0 weeks gestational age at birth and have a birth weight < 1500 grams.
• Mothers will be included if they are (1) older than 15 years, (2) able to communicate in English or Spanish, (3) primary caregivers of the newborn.

Exclusion Criteria:

• Neonates will be excluded if they (1) are born > 32/0 weeks GA, (2) weigh more than 1,500 grams at birth, (3) have congenital abnormalities, (2) will be discharged before day 7 of life, (3) have a positive urine drug screen, or (4) are being placed for adoption after discharge from the hospital.
• Mothers will be excluded if they have (1) narcotic or injection drug dependence or (2) a documented serious health (e.g., cancer or HIV positive) or psychological (e.g., schizophrenia) problem.

Mothers will be eligible for consent if they are a patient in the Duke University Hospital Labor & Delivery department and meet all eligibility criteria. Potential mothers will be approached about the study before delivery or within 72 hours after delivery. 150 mother-VLBW infant pairs, a total of 300 participants, will be recruited for the final sample size of 120 pairs. English or Spanish speaking mothers may participate. If the mother is between 15-17 years of age, a minor mother consent will be used. If the mother is Spanish speaking, a Spanish short form consent will be used with a Spanish interpreter. If the mother is pre-consented, the infant may or may not be enrolled at delivery. The infant could be excluded if he/she is delivered at a gestation or weight that is outside of study limits, or if she/he has a severe health problem/congenital anomaly detected at birth.