Pregnancy Nausea – Why does it occur?

Nausea in pregnancy is a common symptom. It is worst in the first trimester of pregnancy where most of us refer to it as morning sickness. Here the nausea, often accompanied by vomiting, tend to be worse during the first half of the day. However, some women may experience this nausea throughout pregnancy. Nausea may also arise again in the latter parts of pregnancy but often for different reasons from the morning sickness of early pregnancy. Whatever the cause, nausea can significantly upset the life of a pregnant women, hamper normal eating which is important for the growing baby and when accompanied by vomiting it can even lead to serious complications for the mother and unborn child.

Reasons for Pregnancy Nausea


Early pregnancy nausea starts from as soon as a few days after conception. It may signal pregnancy even when a woman has not other symptoms as yet. Typically this is the morning sickness that is the hallmark of pregnancy. But do not be surprised if you do have this early in pregnancy. Some women are fortunate to have very mild or even no nausea.

The nausea in early pregnancy is a result of the hormonal changes that start immediately from the time of conception. It is believed to be due to the rapidly rising levels of human chorionic gonadotropic (HCG). At this time the mother’s body is not accustomed to this hormone which increases exponentially every few days. The higher than normal levels of estrogen and progesterone may also contribute to morning sickness in early pregnancy.

Gradually your body will adapt to these hormones and morning sickness will subside anywhere from a few weeks after conception or even after the first trimester. This is normal. However, some women experience severe nausea and vomiting throughout the first trimester and beyond, which can be dangerous. Excessive nausea and profuse vomiting is known as hyperemesis gravidarum. It needs to be treated medically as it can put the mother’s health at risk and even jeopardize the pregnancy.


Pregnancy that tends to start up later in pregnancy may also be due to hormones. However, often this nausea is related to acid reflux. The spilling of the acidic stomach contents into the esophagus. While heartburn is a typical symptom of acid reflux or gastroesophageal reflux disease (GERD), it is not uncommon for it to be absent despite there being severe nausea. Reflux later in pregnancy largely occurs as a result of the growing uterus increasing pressure within the abdomen.

Coupled with the effects of hormones, this slackens the lower esophageal sphincter (LES) and also pushes the contents upwards out of the stomach. Acid reflux in pregnancy is very common. Most women find that it is the worst later in pregnancy and it can be severe enough to affect normal eating patterns and sleep. The reflux may naturally persist after childbirth but gradually subsides if other factors for acid reflux are not present.


Another often ignored cause of nausea in pregnancy, both early and late pregnancy, is anxiety on the part of the mother. Having a baby is a life changing event and coupled with the fear of childbirth and life thereafter, anxiety is common. This may further contribute to reflux but also contribute to nausea, sometimes as a result of the psychological aspect.

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