Pregnancy

This article is about pregnancy in humans. For other mammals, see Pregnancy (mammals). For fish, see Pregnancy in fish.
"Pregnant" redirects here. For other uses, see Pregnant (disambiguation).

Pregnancy
Other namesGestation
A woman in the third trimester of pregnancy
SpecialtyObstetrics, midwifery
SymptomsMissed periods, tender breasts, nausea and vomiting, hunger, frequent urination[1]
ComplicationsMiscarriage, high blood pressure of pregnancy, gestational diabetes, iron-deficiency anemia, severe nausea and vomiting[2][3]
Duration~40 weeks from the last menstrual period (38 weeks after conception)[4][5]
CausesSexual intercourse, assisted reproductive technology[6]
Diagnostic methodPregnancy test[7]
PreventionBirth control (including emergency contraception)[8]
TreatmentPrenatal care,[9] abortion[8]
MedicationFolic acid, iron supplements[9][10]
Frequency213 million (2012)[11]
DeathsPositive decrease 230,600 (2016)[12]

Pregnancy is the time during which one or more offspring develops (gestates) inside a woman's uterus (womb).[4][13] A multiple pregnancy involves more than one offspring, such as with twins.[14]

Pregnancy usually occurs by sexual intercourse, but can also occur through assisted reproductive technology procedures.[6] A pregnancy may end in a live birth, a miscarriage, an induced abortion, or a stillbirth. Childbirth typically occurs around 40 weeks from the start of the last menstrual period (LMP), a span known as the gestational age.[4][5] This is just over nine months. Counting by fertilization age, the length is about 38 weeks.[5][13] Pregnancy is "the presence of an implanted human embryo or fetus in the uterus"; implantation occurs on average 8–9 days after fertilization.[15] An embryo is the term for the developing offspring during the first seven weeks following implantation (i.e. ten weeks' gestational age), after which the term fetus is used until birth.[5]

Signs and symptoms of early pregnancy may include missed periods, tender breasts, morning sickness (nausea and vomiting), hunger, implantation bleeding, and frequent urination.[1] Pregnancy may be confirmed with a pregnancy test.[7] Methods of birth control—or, more accurately, contraception—are used to avoid pregnancy.

Pregnancy is divided into three trimesters of approximately three months each. The first trimester includes conception, which is when the sperm fertilizes the egg. The fertilized egg then travels down the fallopian tube and attaches to the inside of the uterus, where it begins to form the embryo and placenta. During the first trimester, the possibility of miscarriage (natural death of embryo or fetus) is at its highest. Around the middle of the second trimester, movement of the fetus may be felt. At 28 weeks, more than 90% of babies can survive outside of the uterus if provided with high-quality medical care, though babies born at this time will likely experience serious health complications such as heart and respiratory problems and long-term intellectual and developmental disabilities.

Prenatal care improves pregnancy outcomes.[9] Nutrition during pregnancy is important to ensure healthy growth of the fetus.[16] Prenatal care may also include avoiding recreational drugs (including tobacco and alcohol), taking regular exercise, having blood tests, and regular physical examinations.[9] Complications of pregnancy may include disorders of high blood pressure, gestational diabetes, iron-deficiency anemia, and severe nausea and vomiting.[3] In the ideal childbirth, labor begins on its own "at term".[17] Babies born before 37 weeks are "preterm" and at higher risk of health problems such as cerebral palsy.[4] Babies born between weeks 37 and 39 are considered "early term" while those born between weeks 39 and 41 are considered "full term".[4] Babies born between weeks 41 and 42 weeks are considered "late-term" while after 42 weeks they are considered "post-term".[4] Delivery before 39 weeks by labor induction or caesarean section is not recommended unless required for other medical reasons.[18]

  1. ^ a b "What are some common signs of pregnancy?". Eunice Kennedy Shriver National Institute of Child Health and Human Development. 12 July 2013. Archived from the original on 19 March 2015. Retrieved 14 March 2015.
  2. ^ The Johns Hopkins Manual of Gynecology and Obstetrics (4 ed.). Lippincott Williams & Wilkins. 2012. p. 438. ISBN 978-1-4511-4801-5. Archived from the original on 10 September 2017.
  3. ^ a b "What are some common complications of pregnancy?". Eunice Kennedy Shriver National Institute of Child Health and Human Development. 12 July 2013. Archived from the original on 26 February 2015. Retrieved 14 March 2015.
  4. ^ a b c d e f "Pregnancy: Condition Information". Eunice Kennedy Shriver National Institute of Child Health and Human Development. 19 December 2013. Archived from the original on 19 March 2015. Retrieved 14 March 2015.
  5. ^ a b c d Abman SH (2011). Fetal and neonatal physiology (4th ed.). Philadelphia: Elsevier/Saunders. pp. 46–47. ISBN 978-1-4160-3479-7.
  6. ^ a b Shehan CL (2016). The Wiley Blackwell Encyclopedia of Family Studies, 4 Volume Set. John Wiley & Sons. p. 406. ISBN 978-0-470-65845-1. Archived from the original on 10 September 2017.
  7. ^ a b "How do I know if I'm pregnant?". Eunice Kennedy Shriver National Institute of Child Health and Human Development. 30 November 2012. Archived from the original on 2 April 2015. Retrieved 14 March 2015.
  8. ^ a b Taylor D, James EA (2011). "An evidence-based guideline for unintended pregnancy prevention". Journal of Obstetric, Gynecologic, and Neonatal Nursing. 40 (6): 782–793. doi:10.1111/j.1552-6909.2011.01296.x. ISSN 0090-0311. PMC 3266470. PMID 22092349.
  9. ^ a b c d "What is prenatal care and why is it important?". Eunice Kennedy Shriver National Institute of Child Health and Human Development. 12 July 2013. Archived from the original on 2 April 2015. Retrieved 14 March 2015.
  10. ^ Keats EC, Haider BA, Tam E, Bhutta ZA (March 2019). "Multiple-micronutrient supplementation for women during pregnancy". The Cochrane Database of Systematic Reviews. 3 (3): CD004905. doi:10.1002/14651858.CD004905.pub6. PMC 6418471. PMID 30873598.
  11. ^ Sedgh G, Singh S, Hussain R (September 2014). "Intended and unintended pregnancies worldwide in 2012 and recent trends". Studies in Family Planning. 45 (3): 301–314. doi:10.1111/j.1728-4465.2014.00393.x. PMC 4727534. PMID 25207494.
  12. ^ Naghavi M, Abajobir AA, Abbafati C, Abbas KM, Abd-Allah F, Abera SF, et al. (GBD 2016 Causes of Death Collaborators) (September 2017). "Global, regional, and national age-sex specific mortality for 264 causes of death, 1980-2016: a systematic analysis for the Global Burden of Disease Study 2016". Lancet. 390 (10100): 1151–1210. doi:10.1016/S0140-6736(17)32152-9. PMC 5605883. PMID 28919116.
  13. ^ a b Mosby (2009). Mosby's Pocket Dictionary of Medicine, Nursing & Health Professions - E-Book. Elsevier Health Sciences. p. 1078. ISBN 978-0-323-06604-4.
  14. ^ Wylie L (2005). Essential anatomy and physiology in maternity care (Second ed.). Edinburgh: Churchill Livingstone. p. 172. ISBN 978-0-443-10041-3. Archived from the original on 10 September 2017.
  15. ^ Massachusetts General Laws c.112 § 12K: Definitions applicable to Secs. 12L to 12U, Commonwealth of Massachusetts, 2022
  16. ^ Lammi-Keefe CJ, Couch SC, Philipson EH, eds. (2008). Handbook of Nutrition and Pregnancy. Nutrition and health. Totowa, NJ: Humana Press. p. 28. doi:10.1007/978-1-59745-112-3. ISBN 978-1-59745-112-3.
  17. ^ American Congress of Obstetricians and Gynecologists (February 2013), "Five Things Physicians and Patients Should Question", Choosing Wisely: an initiative of the ABIM Foundation, American Congress of Obstetricians and Gynecologists, archived from the original on 1 September 2013, retrieved 1 August 2013
  18. ^ World Health Organization (November 2014). "Preterm birth Fact sheet N°363". who.int. Archived from the original on 7 March 2015. Retrieved 6 March 2015.