trimester

(noun)

A period of approximately three months.

Related Terms

Examples of trimester in the following topics:

  • Human Gestation

    • The gestation period is divided into three equal periods or trimesters.
    • Internal organs and body structures begin to develop during the first trimester.
    • During the second trimester, the fetus grows to about 30 cm (12 inches) .
    • The mother will be at her most uncomfortable during this trimester.
    • Describe the development of the human fetus from fertilization through the third trimester

  • Anatomical Changes

    • Breast tenderness is common during the first trimester.
    • The first 12 weeks of pregnancy are known as the first trimester.
    • During this trimester, fetal development can be divided into different stages.
    • Weeks 13 to 28 of the pregnancy are called the second trimester.
    • By the end of the second trimester, the expanding uterus has created a visible baby bump.

  • Introduction to Pregnancy and Human Development

    • In many societies' medical or legal definitions, human pregnancy is somewhat arbitrarily divided into three trimester periods as a means to simplify reference to the different stages of prenatal development.
    • The first trimester carries the highest risk of miscarriage (natural death of embryo or fetus).
    • During the second trimester, the development of the fetus is more easily monitored.
    • The beginning of the third trimester often approximates the point of viability, or the ability of the fetus to survive, with or without medical help, outside of the uterus.

  • Placenta Previa

    • It can sometimes occur in the latter part of the first trimester, but usually occurs during the second or third trimester.
    • In the last trimester of pregnancy, the isthmus of the uterus unfolds and forms the lower segment.

  • The Role of Genes in Prenatal Development

    • Prenatal development is also organized into trimesters: the first trimester ends with the end of the embryonic stage, the second trimester ends at week 20, and the third trimester ends at birth.

  • Labor and Birth

    • Toward the end of the third trimester, estrogen causes receptors on the uterine wall to develop and bind the hormone oxytocin.
    • The mother's mammary glands go through changes during the third trimester to prepare for lactation and breastfeeding.

  • Prenatal Brain Development

    • Prenatal development is also organized into three equal trimesters, which do not correspond with the three stages.
    • The first trimester ends with the end of the embryonic stage, the second trimester ends at week 20, and the third trimester ends at birth.

  • Prenatal Diagnostic Tests

    • Since chorionic villus sampling is performed earlier in the pregnancy than amniocentesis, typically during the first trimester, it can reasonably be expected that there will be a higher rate of miscarriage after chorionic villus sampling than after amniocentesis.
    • Other testing may combine a first trimester blood test with one done in the second trimester to determine if further action needs to be taken.

  • Metabolic Changes

    • Gestational diabetes (or gestational diabetes mellitus, GDM) is a condition in which women without previously diagnosed diabetes exhibit high blood glucose levels during pregnancy (especially during the third trimester).

  • Developmental Changes in Fluids

    • Further research results indicate that the central cholinergic mechanism is established and functional in the regulation of the hypothalamic neuropeptides during the final trimester of pregnancy.