Phenomena and Processes

Pregnancy Trimesters

The three approximately equal periods of a normal human PREGNANCY. Each trimester is about three months or 13 to 14 weeks in duration depending on the designation of the first day of gestation.

National Library of MedicineMedical Subject Headings2026

Structured Summary

Abstract

The three approximately equal periods of a normal human PREGNANCY. Each trimester is about three months or 13 to 14 weeks in duration depending on the designation of the first day of gestation.

MeSH Record

Classification

Related Concepts

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MeSH Record

Synonyms

3 entry terms
  • Trimesters, Pregnancy
  • Pregnancy Trimester
  • Trimester, Pregnancy

MeSH Record

Aspects Covered

11 allowable subheadings

Indexed with the subheadings blood, cerebrospinal fluid, drug effects, ethnology, genetics, immunology, metabolism, physiology, psychology, radiation effects, urine.

MeSH Record

Indexing Annotation

human only; general or unspecified; prefer specifics; trimesters are indexed only when the point of the article or substantively discussed: they are not sought out routinely nor indexed when merely mentioned

MeSH Record

History Note

98; use explode 1975-97

MeSH Record

Previous Indexing

  • Gestational Age (1968-1974)
  • Pregnancy (1966-1974)
  • Time Factors (1967-1974)
  • specific trimester (1975-1997)

MeSH Hierarchy

Tree Number

  1. G08.686.707w

AMA Style

References

  1. National Library of Medicine. Pregnancy Trimesters. Medical Subject Headings (MeSH). 2026. Unique ID D011264. http://id.nlm.nih.gov/mesh/2026/D011264
  2. Pregnancy Trimesters. In: Wikipedia. https://en.wikipedia.org/wiki/Trimester_(pregnancy)
  3. Pregnancy Trimesters. In: Wikidata. https://www.wikidata.org/wiki/Q33083015