TABLE 2.

Correlations Between Birth Weight, Ponderal Index, Gender, Socioeconomic Status, Caregiver Perceptions of Infant Irritability, and Maternal Responsiveness With Change in Weight and Scores on Measures of Development and Behavior

	Birth Weight	Ponderal Index	Gender*	Socioeconomic Status	Infant Irritability†	Maternal Responsiveness
6 mo
Weight change	0.19‡	−0.03	−0.27||	0.20§
MDI	0.40||	0.02	−0.07	0.02
PDI	0.43||	0.03	−0.05	−0.01
Orientation/engagement	0.40||	−0.07	−0.06	−0.03
Emotional regulation	0.31||	−0.08	0.02	−0.04
Motor quality	0.29||	−0.05	−0.02	0.04
10 mo
Weight change	0.20§	−0.04	−0.25||	0.20‡	−0.03	0.05
MDI	0.27§	0.07	−0.18‡	0.27§	−0.16‡	0.18‡
PDI	0.45||	−0.03	−0.11	0.14	−0.19‡	0.15‡
Orientation/engagement	0.24§	0.04	−0.14	0.17†	−0.08	0.13
Emotional regulation	0.21§	0.06	−0.18‡	0.10	−0.12	0.11
Motor quality	0.29||		−0.04	0.12	−0.14	0.12

MDI indicates Mental Development Index; PDI, Psychomotor Development Index.

^*Male = 1, female = 2.

^†Low scores optimal.

^‡P < .05.

^§P < .01.

^||P < .001.