Vomiting During Pregnancy – Obstetric and Non-Obstetric Causes

Nausea and vomiting during pregnancy, especially in the early months, is a common phenomenon. Most women suffer from symptoms of morning sickness in the first trimester (first twelve weeks) of pregnancy. After this period, the symptoms usually stop and most women go on to deliver a normal healthy baby without any complications. If, however, the vomiting is severe and prolonged, associated with dehydration and weight loss, it could point to a more serious condition known as hyperemesis gravidarum.

Causes of Pregnancy Vomiting

The exact cause of vomiting during pregnancy is not known. It could be due to a number of factors including :

  • Fluctuating hormone levels during pregnancy (human chorionic gonadotropin, estrogen and progesterone) may possibly cause vomiting by acting directly or indirectly on the chemoreceptor trigger zone or causes contractions of the abdominal and/or diaphragm muscles.
  • Psychological factors, such as stress, may be a contributing factor.
  • Helicobacter pylori infection which is associated with gastritis and peptic ulcer disease has been implicated in causing vomiting during pregnancy.
  • Multiple pregnancies – twins, triplets or more may increase chances of pregnancy vomiting, presumably due to excess of pregnancy hormones.
  • Low blood sugar.
  • Prenatal vitamins containing iron sometimes cause nausea and vomiting.

Vomiting during pregnancy can be divided into obstetric or pregnancy-related vomiting and non-obstetric causes of vomiting. Vomiting that begins during the first trimester of pregnancy is more likely to be pregnancy-induced, while a non-obstetric cause should be suspected if vomiting starts after the first trimester or if it is accompanied by fever, diarrhea, abdominal pain, headache, or other symptoms.

Obstetric Causes of Vomiting

  • Morning sickness.
  • Hyperemesis gravidarum.
  • Hydatidiform mole.

Non-obstetric Causes of Vomiting

  • Acute gastroenteritis.
  • Urinary tract infection (UTI) or pyelonephritis.
  • Bowel obstruction.
  • Migraine.
  • Appendicitis.
  • Cholecystitis.

Morning Sickness

This is the most common type of pregnancy vomiting. Symptoms include mild to moderate nausea and/or vomiting. Any odor, such as the smell of food or cooking, can aggravate or bring on the symptoms.  Although it is called morning sickness, the symptoms may occur any time of the day.

The symptoms are usually intermittent, coming and going at different times of the day.  It usually begins in the first month of pregnancy and improves by the fourth month. Rarely, it continues throughout pregnancy. Most cases of morning sickness do not cause any harm to mother or baby.

Hyperemesis Gravidarum

This is a more severe form of vomiting during pregnancy. It is a rare complication of pregnancy. Symptoms include prolonged and persistent vomiting and can lead to dehydration. It may lead to bile vomiting which appears as bright yellow to green in color. Weight loss of more than 5% of pre-pregnancy weight can be cause for alarm. Ketonuria may be present and an electrolyte disturbance is likely.

It is more common in the first half of pregnancy and usually improves in later half of pregnancy. Sometimes it may persist for longer. There is a risk of a low birth weight baby or preterm labor in severe cases.

Hydatidiform Mole

Hydatidiform mole or molar pregnancy is the growth of an abnormal fertilized egg which does not develop into a fetus. Severe nausea and vomiting is usually present. Other signs and symptoms include :

  • Uterus size is larger than expected for the stage of pregnancy.
  • Absence of fetal movement.
  • No fetal heart sounds.
  • Sometimes there is passage of grape-like tissue from the vagina.
  • Vaginal bleeding is common.

Related Articles

  1. Pregnancy Vomiting Remedies and Treatment
  2. Headache, Nausea and Vomiting
  3. What is Vomiting?
  4. Vomiting Bile

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