pregnancy

Introduction & Top Questions
The normal events of pregnancy
- Initiation of pregnancy
- Diagnosis of pregnancy
  - Symptoms and signs; biological tests
  - Conditions that may be mistaken for pregnancy
  - Duration of pregnancy
- Anatomic and physiologic changes of normal pregnancy
  - Changes in organs and tissues directly associated with childbearing
    - Ovaries
    - The uterus and the development of the placenta
    - Uterine tubes
    - Vagina
    - External genital structures
    - Other pelvic tissues
    - Breasts
  - Anatomic and physiologic changes in other organs and tissues
    - Cardiovascular and lymphatic systems
    - Respiratory tract
    - Gastrointestinal tract
    - Liver
    - Urinary tract
    - Blood
    - Endocrine system
    - Skin
  - Metabolic changes
    - The basal metabolic rate
    - Weight
    - Protein
    - Carbohydrates
    - Fat
    - Water
    - Minerals
- Prenatal care and testing
  - Ultrasound
  - Amniocentesis
  - Chorionic villi sampling
  - Alpha-fetoprotein screening
Abnormal changes in pregnancy
- Ectopic pregnancy
- Abortion
- Systemic diseases and pregnancy
  - Heart disease
  - Endocrine diseases
    - Diabetes
    - Thyroid disease
    - Pituitary disorders
    - Adrenal glands
  - Urinary tract diseases
  - Pulmonary disease
  - Gastrointestinal diseases
  - Nervous system disorders
- Diseases of pregnancy
  - Hypertensive disorders of pregnancy
  - Gestational diabetes
  - Diseases of the placenta
    - Placenta praevia
    - Abruptio placentae
    - Placental infarction
    - Placenta accreta
    - Placental cysts and benign tumors
    - Inflammation of the placenta
    - Placental anomalies
  - Anomalies of the umbilical cord
  - Abnormalities of the amniotic fluid
    - Hydramnios
    - Oligohydramnios
  - Trophoblastic disease
    - Hydatidiform mole
    - Choriocarcinoma

References & Edit History Related Topics

Images, Videos & Interactives

Close-up of a home pregnancy test device showing a blue plus sign in the result window, indicating a positive result for pregnancy.

Diagram showing the female reproductive system with labeled ovaries, fallopian tubes, uterus, and vagina, alongside hormone pathways and the process from ovulation to fertilization and early embryo development.

How does a home pregnancy test work?

Learn how researchers use biobanks, such as the Improved Pregnancy Outcomes by Early Detection study, or IMPROvED to improve maternal and newborn outcomes

A pregnant woman lies on an exam table smiling while a healthcare professional performs an ultrasound, with the baby's image visible on the monitor.

Cross-sectional medical illustration of a human uterus at seven weeks of pregnancy, showing the developing embryo inside the amniotic sac, placenta, umbilical cord, uterine wall layers, cervix, and vagina, with labeled anatomical structures related to gestation and embryology.

Three labeled cross-section diagrams show the development of a human embryo implanted in the uterine lining at 7.5, 13, and 23 days, highlighting structures such as the embryonic disk, amniotic cavity, yolk sac, trophoblast, and chorion.

At a Glance

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pregnancy summary

pregnancy: Media

medicine

Videos

How does a home pregnancy test work?

How does a home pregnancy test work?

How pregnancy tests work.

Video: © American Chemical Society (A Britannica Publishing Partner)

Learn how researchers use biobanks, such as the Improved Pregnancy Outcomes by Early Detection study, or IMPROvED to improve maternal and newborn outcomes

Learn how researchers use biobanks, such as the Improved Pregnancy Outcomes by Early Detection study, or IMPROvED to improve maternal and newborn outcomes

A discussion about obstetric and gynecological researchers using “biobanks” to improve...

Video: University College Cork, Ireland (A Britannica Publishing Partner)

Causes of morning sickness explained

Causes of morning sickness explained

Learn what causes morning sickness, or nausea, in pregnant women.

Video: © American Chemical Society (A Britannica Publishing Partner)

How does the Rh factor affect pregnancies?

How does the Rh factor affect pregnancies?

Overview of the Rh factor and why pregnant women should be tested for it before giving...

Video: Encyclopædia Britannica, Inc.

Images

Close-up of a home pregnancy test device showing a blue plus sign in the result window, indicating a positive result for pregnancy.

Home pregnancy tests

Devices for individual use at home detect pregnancy by measuring levels of the hormone...

© Hadi Djunaedi/Shutterstock.com

Diagram showing the female reproductive system with labeled ovaries, fallopian tubes, uterus, and vagina, alongside hormone pathways and the process from ovulation to fertilization and early embryo development.

Initiation of pregnancy: fertilization and implantation

Major structures and hormones involved in the initiation of pregnancy. Also seen,...

Encyclopædia Britannica, Inc.

A pregnant woman lies on an exam table smiling while a healthcare professional performs an ultrasound, with the baby's image visible on the monitor.

Ultrasound

A pregnant woman undergoes an ultrasound, which uses very-high-frequency sound waves...

© Jim Craigmyle—Stone/Getty Images

pregnancy

pregnancy

Pregnancy, encompassing the process from fertilization to birth, lasts an average...

© Michel Borges/Fotolia

Cross-sectional medical illustration of a human uterus at seven weeks of pregnancy, showing the developing embryo inside the amniotic sac, placenta, umbilical cord, uterine wall layers, cervix, and vagina, with labeled anatomical structures related to gestation and embryology.

embryonic development

The state of development of a human embryo at the seventh week of pregnancy.

Encyclopædia Britannica, Inc.

Fetal growth

Fetal growth

Growth of the human fetus from the fourth month to the ninth month of pregnancy.

Encyclopædia Britannica, Inc.

Three labeled cross-section diagrams show the development of a human embryo implanted in the uterine lining at 7.5, 13, and 23 days, highlighting structures such as the embryonic disk, amniotic cavity, yolk sac, trophoblast, and chorion.

implanted human embryo

Development of the human embryo, shown as half-section depictions of embryos implanted...

Encyclopædia Britannica, Inc.

Diagram showing human embryological and fetal development in three stages: at six weeks, the embryo is enclosed within halved amnion, chorion, and uterus; another view at six weeks highlights the formation of the umbilical cord; at three months, the fetus is shown within the halved amnion, chorion, and uterus, with the placenta and umbilical cord labeled.

umbilical cord formation

Human embryological and fetal development. An embryo of six weeks is depicted within...

Encyclopædia Britannica, Inc.

Full-term human fetus in the uterus

Full-term human fetus in the uterus

Full-term fetus in the uterus. The amnion, formed from the inner embryonic membrane,...

© Merriam-Webster Inc.

Interactives

Pregnancy

Pregnancy

The normal events of pregnancy.

Encyclopædia Britannica, Inc.

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