In the weeks following delivery, a woman must recover from childbirth, adapt to changing hormones, and learn to feed and care for her newborn. During this “4th Trimester,” many women experience considerable challenges, including fatigue, pain, breastfeeding difficulties, depression, lack of sexual desire and incontinence. Amid these concerns, postpartum care is often fragmented among maternal and pediatric providers, and 20 to 40% of women do not attend a postpartum visit. Rising maternal mortality and morbidity in the US have made this work an even greater priority. Our goal is to bring together mothers, health care providers, and other stakeholders to define what families need most during the 4th Trimester. Our stakeholder teams will determine priority health themes and systems. Based on the unmet health priorities that stakeholders identify, we will design research studies to deliver optimal care during this critical period, improving outcomes for mothers, infants and families.