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Pregnancy

Last updated: August 16, 2023

Summarytoggle arrow icon

Pregnancy begins with the fertilization of the ovum and its subsequent implantation into the uterine wall. The duration of pregnancy is counted in weeks of gestation from the first day of the last menstrual period and on average lasts 40 weeks. Presumptive signs of pregnancy include amenorrhea, nausea and vomiting, and breast enlargement and tenderness. Preconception counseling assists in the planning of pregnancy through education and risk assessment to help ensure best possible outcomes. Pregnancy can be confirmed definitively via positive serum or urine hCG tests and detection of the embryo on ultrasound. Women experience several physiological changes during pregnancy (e.g., increased plasma volume, venous stasis, increased insulin secretion, increased oxygen demand), which can lead to symptoms and conditions that may require treatment (e.g., peripheral edema, insulin resistance, hypercoagulability, dyspnea).

Management of pregnancy, including counseling, examinations, ultrasound, and care of high-risk pregnancies, is covered separately in the article “Prenatal care.”

Definitionstoggle arrow icon

Gravidity, parity, and duration of pregnancy [1]

  • Gravidity: the number of times a woman has been pregnant, regardless of pregnancy outcome
    • Nulligravidity: no history of pregnancy
    • Primigravidity: history of one pregnancy
    • Multigravidity: history of two or more pregnancies
  • Parity: the number of pregnancies that a woman carries beyond 20 weeks of gestation and ends with the birth of an infant weighing > 500 g
    • Nulliparity: no history of a completed pregnancy that reached beyond 20 weeks' gestation or ended with a birth weight of > 500 g
    • Primiparity: a history of one completed pregnancy that reached beyond 20 weeks' gestation or ended with a birth weight of > 500 g
    • Multiparity: a history of more than one pregnancy that reached beyond 20 weeks' gestation or ended with a birth weight of > 500 g
  • Fetal age [2]
    • Counted as completed weeks of gestation and completed days (0–6) of the current week of pregnancy
    • Gestational age: estimated fetal age (in weeks and days) calculated from the first day of the last menstrual period
    • Conceptional age: the age (in weeks and days) of the fetus calculated from the day of conception (fertilization)
  • Duration of pregnancy
  • Gestional age at birth
  • Trimesters of pregnancy
    • First trimester (weeks 1–13)
    • Second trimester (weeks 14–26)
    • Third trimester (weeks 27–40)

Recording systems

Overview of recording systems
Recording system Description Example
TPAL Obstetric recording system that comprises: term births (T), premature births (P), abortions (A), and living children (L) A woman who reports 5 pregnancies with two miscarriages at weeks 11 and 14 of pregnancy, one medical abortion, one delivery at week 39 of pregnancy of a child weighing 3100 g, one delivery at week 29 of pregnancy of a child weighing 2100 g who died soon after birth should be reported as: T1, P1, A3, L1.
GTPAL An extension of the TPAL recording system that also includes gravidity (G) A woman who reports 5 pregnancies with two miscarriages at weeks 11 and 14 of pregnancy, one medical abortion, one delivery at week 39 of pregnancy of a child weighing 3100 g, one delivery at week 29 of pregnancy of a child weighing 2100 g who died soon after birth should be reported as: G5, T1, P1, A3, L1.
GP Obstetric recording system that comprises: gravidities (G) and parities (P) A woman who reports 4 pregnancies and one delivery of an infant weighing 2100 g at week 32 of pregnancy is reported as: G4, P1.

Clinical signs of early pregnancytoggle arrow icon

Presumptive signs

Probable signs [3][4]

Overview
Signs Physical findings Weeks of pregnancy
Goodell Cervical softening First 4 weeks
Hegar Softening of the lower segment of the uterus Between 6–8 weeks
Ladin Softening of the midline of the uterus First 6 weeks
Chadwick Bluish discoloration of vagina and cervix Between 6–8 weeks
Telangiectasias and palmar erythema Small blood vessels and redness of the palms First 4 weeks
Chloasma Hyperpigmentation of the face (forehead, cheeks, nose) First 16 weeks

Diagnosis of pregnancytoggle arrow icon

Human chorionic gonadotropin (hCG)

Interpretation of β-hCG findings

Overview

β-hCG findings

Description
Normal
Low Maternal
Fetal
High Maternal
Fetal
False-positive

Ultrasound findings in normal pregnancy (abdominal or transvaginal) [6]

See also “Prenatal ultrasound” and “Gestational age and estimated date of delivery.”

Physiological changes during pregnancytoggle arrow icon

Cardiovascular system [7][8]

A physiological systolic murmur may be heard due to increased cardiac output and increased plasma volume.

Respiratory system [9]

Renal system [8][10]

Endocrine system [8][11][12]

Hematologic system [8][13][14]

Physiological hypercoagulability during pregnancy leads to an increased risk of thrombosis. Patients with thrombophilia should receive adequate thrombosis prophylaxis.

Gastrointestinal system [8]

Musculoskeletal system [8]

Skin

Reproductive system

Fetal complications during pregnancytoggle arrow icon

Oligohydramnios [15]

Potter babies cannot Pee.

POTTER sequence: Pulmonary hypoplasia (lethal), Oligohydramnios (origin), Twisted facies, Twisted skin, Extremity deformities, and Renal agenesis (classic form).

Polyhydramnios [17]

Other complications

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Referencestoggle arrow icon

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  2. Spong CY. Defining “Term” Pregnancy. JAMA. 2013; 309 (23): p.2445.doi: 10.1001/jama.2013.6235 . | Open in Read by QxMD
  3. Anthony J, Osman A, Sani M. Valvular heart disease in pregnancy. Cardiovasc J Afr. 2016; 27 (2): p.111-118.doi: 10.5830/cvja-2016-052 . | Open in Read by QxMD
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  5. LoMauro A, Aliverti A. Respiratory physiology of pregnancy. Breathe. 2015; 11 (4): p.297-301.doi: 10.1183/20734735.008615 . | Open in Read by QxMD
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  11. Tunzy, Gray. Common Skin Conditions During Pregnancy. American Family Physician. 2007.
  12. Probable signs of pregnancy. https://brooksidepress.org/ob_newborn_care_1/?page_id=288&cn-reloaded=1. Updated: July 30, 2016. Accessed: September 2, 2020.
  13. Cohen LS. Diagnostic Ultrasound in the First Trimester of Pregnancy. The Global Library of Women's Medicine. 2009.doi: 10.3843/glowm.10094 . | Open in Read by QxMD
  14. Tezuka et al.. Embryonic Heart Rates: Development in Early First Trimester and Clinical Evaluation. Gynecol Obstet Invest. 1991; 32 (4): p.210-212.doi: 10.1159/000293033 . | Open in Read by QxMD
  15. Dubil EA, Magann EF. Amniotic fluid as a vital sign for fetal wellbeing. Australasian Journal of Ultrasound in Medicine. 2013; 16 (2): p.62-70.doi: 10.1002/j.2205-0140.2013.tb00167.x . | Open in Read by QxMD
  16. Mousavi AS, Hashemi N, Kashanian M, Sheikhansari N, Bordbar A, Parashi S. Comparison between maternal and neonatal outcome of PPROM in the cases of amniotic fluid index (AFI) of more and less than 5 cm. J Obstet Gynaecol (Lahore). 2018; 38 (5): p.611-615.doi: 10.1080/01443615.2017.1394280 . | Open in Read by QxMD
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