Nausea and vomiting are common during pregnancy, often called “morning sickness” though they can occur at any time. This phenomenon affects over 70% of pregnant individuals. It is a normal physiological response to the changes occurring in early pregnancy.
When Pregnancy Nausea Typically Begins
Pregnancy nausea commonly begins between weeks four and six of gestation, often two weeks after a missed menstrual period. Symptoms can appear gradually or suddenly. Nausea and vomiting usually intensify, peaking between weeks 8 and 11 of pregnancy, aligning with peak levels of certain pregnancy hormones.
For most individuals, these sensations begin to subside by the second trimester, typically around 14 to 20 weeks of pregnancy. However, some may experience nausea and vomiting for a longer duration, with symptoms persisting into the second or even third trimester, or throughout the entire pregnancy. The exact timeline can vary.
What Influences Nausea During Pregnancy
Significant hormonal shifts early in gestation contribute to pregnancy nausea. The rapid increase in human chorionic gonadotropin (hCG) levels, a hormone produced by the placenta, is often implicated. hCG levels typically peak around 9 to 10 weeks, correlating with peak nausea symptoms.
Other hormones like estrogen and progesterone also rise, playing a role. Progesterone can relax the muscles of the digestive tract, potentially slowing digestion and contributing to nausea. Many pregnant individuals develop hyperosmia, a heightened sense of smell, which can make odors overwhelming and trigger nausea. This sensitivity is linked to changing hormone levels.
Fluctuations in blood sugar levels may also influence nausea. In early pregnancy, glucose levels can sometimes drop due to increased blood volume, potentially contributing to nausea. While the precise cause is not fully understood, these physiological changes are central to pregnancy nausea.
Understanding Different Levels of Nausea
Pregnancy nausea varies in severity, from mild discomfort to intense, frequent episodes. Most individuals experience manageable nausea, sometimes with occasional vomiting, without significantly impacting their ability to eat or drink. This level of nausea typically doesn’t harm the pregnant individual or baby.
However, a smaller percentage experience hyperemesis gravidarum (HG), a severe form of nausea and vomiting. HG involves prolonged, excessive daily vomiting leading to significant weight loss, dehydration, and electrolyte imbalances. Dehydration symptoms include thirst, tiredness, dizziness, lightheadedness, and dark, infrequent urination.
Consult a healthcare provider if nausea and vomiting become severe or debilitating. This includes being unable to keep fluids down for 24 hours, significant weight loss, or signs of dehydration. Early medical attention helps manage symptoms and prevent complications.