fourth trimester

noun

: the three month period immediately following giving birth in which the mother typically recovers from childbirth and adjusts to caring for her infant

The "fourth trimester" is a catchphrase used to describe the postpartum period, defined as the first 12 weeks after delivery.

—Meera Varma Simões

Women and their families experience substantial physiological, social, and emotional changes. … Most women would benefit from much closer follow-up during the fourth trimester.

—Ilona T. Goldfarb

especially : the first three months of an infant's life

The concept of the fourth trimester—the three-month period of adjustment for babies to life outside of the womb—was introduced in the late 1970s and then popularized by pediatrician Harvey Karp … in 2002.

—Maggie Overfelt

Examples of fourth trimester in a Sentence

Recent Examples on the Web

An unplanned C-section and ongoing struggles with breastfeeding meant my fourth trimester (the 12 weeks after giving birth, which many experts now believe is as crucial to a mother’s health as their first three trimesters) was filled with unexpected challenges. —Liz Hammond, Vogue, 26 Oct. 2023

Providing comfort during this fourth trimester is essential to ease the transition from womb to world, create bonds between baby and parents, and ensure everyone gets enough (or at least as much as possible) rest. —Samson McDougall, Parents, 8 Sep. 2023

Word History

First Known Use

1970, in the meaning defined above