This study will help researchers learn more about how babies respond to bottle nipples with larger or smaller holes. Researchers guess that infants of mothers with obesity who did not lose weight prior to pregnancy will have the greatest Suck Effect on the challenging compared with the typical nipple.

The researchers will recruit babies from the original cohort in the PLAN study (NCT03244722), regardless of which arms they participated in. However, the researchers will test the study arms from the original PLAN study for effects on the study's dependent variables. Their between-subjects arms included Pre-pregnancy obesity with intensive weight loss intervention, pre-pregnancy obesity with standard of care intervention, and pre-pregnancy healthy weight with no intervention. So, although the researchers are not assigning babies to any arms, their original assignment will still be assessed the study analysis.

To be eligible to participate in this study...

Mother

-Current or previous participation in the PLAN study resulting in a live birth.

Child

• Mother participated in PLAN study during child's gestation
• Infant birth weight (From PLAN study records) appropriate (≥ 3rd percentile and ≤ 97th percentile) for gestational age and sex based on US Natality Data set (Oken et al, BMC Pediatrics 2003).
• Infant is 3.0 to 6.0 months old at Consent.
• Biological mother is legal guardian by maternal report.
• Biological mother is full time custodial guardian by maternal report (versus sharing custody such that infant does not live with her full time).
• Infant typically consumes at least 2 ounces in one feeding from an artificial nipple and bottle at least once per week by maternal report.
• Stated willingness by mother to comply with all study procedures and availability for the duration of the study.

The researchers may consider sharing data but hesitate due to difficulties de-identifying data of small samples. Please contact the study team if you have questions.

Order of nipple size use is counter-balanced, caregivers are blind to nipple size and amount of milk in the bottle (i.e., the bottle is covered) to minimize their influence over the infant's consumption. Research assistants will not be blind to nipple size as they will need to set the bottles ups for the mothers.