The information provided below is for readers based in the United States of America. Readers outside of the United States of America should seek the information from local sources.

What is hypokalemia during pregnancy?

Hypokalemia is a lower-than-normal concentration of potassium [K+] in the blood (actually, in serum, a component of the blood). Potassium is an important electrolyte, and if the concentration is below 3.5 millimoles per liter (mmol/L), then you are hypokalemic. However, effects (symptoms and signs) generally arent noticeable until potassium drops to about 3.0. The situation is very severe if potassium drops to 2.5 mmol/L and lower. Potassium concentration affects virtually every cell in the body, but the most clinically significant effects show up in muscle, including the heart.

Potassium concentration in blood can drop, because you lose potassium, because your intake of potassium decreases, or because potassium moves from the blood into cells. Of these three categories of problems, potassium loss and movement into cells are particularly important during pregnancy, because levels of the hormone aldosterone rise, causing increased extraction of potassium through the kidneys, and because of gastrointestinal disturbances both diarrhea and vomiting. While diarrhea results in water loss, which essentially flushes potassium out of the body, vomiting removes acid from the body, giving you whats called metabolic alkalosis. To compensate for metabolic alkalosis, the body moves acid out of cells, causing potassium to go into cells (where it is already much more concentrated than it is in blood). The body also sends an alkaline electrolyte, called bicarbonate, out through the kidneys, causing potassium excretion. Hormonal changes, stress, and shifting abdominal organs of pregnancy can produce diarrhea (as can laxative abuse), while morning sickness of pregnancy can amount to a great deal of vomiting. On a more extreme scale, a severe type of pregnancy sickness, called hyperemesis gravidarum, features particularly excessive and frequent vomiting.

In addition to digestive-related causes of hypokalemia that are common in pregnancy, hypokalemia has a range of other causes, such as medications (including certain antibiotics, and certain groups of diuretics), high levels of insulin, low levels of magnesium, diabetes insipidus, accidental hypothermia (body temperature drops below normal, not in a controlled way, causing you to shiver), and certain genetic and acquired kidney disorders. Known as hypomagnesemia, low magnesium occurs with more than half of clinically important cases of hypokalemia and can develop if your nutrition is not good. Although dietary deficiency of potassium is not a major cause of hypokalemia, dietary deficiency often exacerbates hypokalemia resulting from other problems, such as vomiting.

How common is hypokalemia during pregnancy?

Hypokalemia is rare during pregnancy. When it does develop, often, it is mild hypokalemia, meaning that your potassium level is in the range of 3.0-3.5, where symptoms are unlikely. Since it is quite dangerous if the levels continue to drop, however, any hypokalemia must be investigated.

How is hypokalemia during pregnancy diagnosed?

Hypokalemia is diagnosed by checking your [K+] as one of the values given in whats called a basic metabolic panel (BMP) performed on a blood sample, also known as a CHEM-7 (or as a CHEM-8 if the calcium level is included). This can also be performed as part of a larger group of tests called a comprehensive metabolic panel (CMP) or a CHEM-14. If your blood tests show hypokalemia (or even prior to blood testing if there is a strong suspicion that you may be hypokalemic), you will also be tested with electrocardiography (ECG). Revealing changes in the hearts electrical activity over time from different directions, ECG typically reveals distinct patterns as hypokalemia worsens. These begin with the decreased amplitude of what doctors call the T wave, which can progress to inversion of the T wave and depression (lowering) of whats called the ST segment, and then the appearance of whats called a U wave.

Does hypokalemia cause problems during pregnancy?

Hypokalemia causes problems with muscle, including the heart muscle, and also the hearts electrical conduction system. Muscle problems can take the form of muscle weakness, cramps, tremors (quivering), and also a severe complication called hypokalemic paraplegia in pregnancy, which can produce a range of symptoms, from weakness and numbness to full paralysis. Another severe complication, which can be fatal, is a breakdown of muscle tissue known as rhabdomyolysis, to which pregnant women may be more prone than others. Heart complications from hypokalemia consist of various types of heart arrhythmias, including atrial fibrillation (quivering of the hearts upper chambers, the atria, which can cause strokes), and torsades de pointes (a particular type of rapid beating of the ventricles, which can cause sudden death). As noted earlier, such problems are not likely, unless your potassium level drops below 2.5 mmol/L.

Does hypokalemia cause problems for the baby?

If the mothers hypokalemia reaches a severe level (below 2.5 mmol/L), the fetus is in danger, because the mothers life is in danger.

What to consider about taking medications when you are pregnant or breastfeeding:

  • The risks to yourself and your baby if you do not treat the hypokalemia 
  • The risks and benefits of each medication you use when you are pregnant
  • The risks and benefits of each medication you use when you are breastfeeding

What should I know about using medication to treat hypokalemia during pregnancy?

If you have mild to moderate hypokalemia ([K+] 2.5-3.5 mmol/L), this can be treated with oral potassium supplementation, either in the form of pills or juices spiked with extra potassium. A common side effect of this is gas and flatulence. If [K+] is below 2.5, then doctors are likely to give you potassium intravenously (IV).

Who should NOT stop taking medication for hypokalemia during pregnancy?

If your potassium has dropped too low, you do need to take potassium as directed by your physician. If oral, potassium should be given gradually to avoid gastrointestinal upset. If IV, potassium should be given at a well-controlled, calculated rate, to avoid the risk of overcompensating and causing hyperkalemia, a potassium level that is too high.

What should I know about choosing a medication for my hypokalemia during pregnancy?

It is important to stay in communication with your health care provider as the release of new studies over time can change the outlook on the role of specific medications during pregnancy.

You may find Pregistrys expert reports about the medications to treat this condition here. Additional information can also be found in the sources listed below.

What should I know about taking a medication for my hypokalemia when I am breastfeeding?

You may take potassium supplementation while you are nursing.

What alternative therapies besides medications can I use to treat my hypokalemia during pregnancy?

If you are only mildly hypokalemic, you may be able to avoid receiving potassium in pill form, if the reason for your potassium loss is dia
gnosed and corrected. In such cases, normal dietary sources of potassium, such as orange juice or bananas, may be enough.

What can I do for myself and my baby when I have hypokalemia during pregnancy?

Follow the instructions of your physician. Be assured that usually, the condition is mild, and usually it is the result of gastrointestinal disturbances that can be corrected.

Resources for hypokalemia in pregnancy:

For more information about hypokalemia during and after pregnancy, contact http://www.womenshealth.gov/ (800-994-9662 [TDD: 888-220-5446]) or contact the following organizations:

Read the whole report
Last Updated: 08-01-2020
General information

It is very common for women to worry about having a miscarriage or giving birth to a child with a birth defect while they are pregnant. Many decisions that women make about their health during pregnancy are made with these concerns in mind.

For many women these concerns are very real. As many as 1 in 5 pregnancies end in a miscarriage, and 1 in 33 babies are born with a birth defect. These rates are considered the background population risk, which means they do not take into consideration anything about the health of the mom, the medications she is taking, or the family history of the mom or the baby’s dad. A number of different things can increase these risks, including taking certain medications during pregnancy.

It is known that most medications, including over-the-counter medications, taken during pregnancy do get passed on to the baby. Fortunately, most medicines are not harmful to the baby and can be safely taken during pregnancy. But there are some that are known to be harmful to a baby’s normal development and growth, especially when they are taken during certain times of the pregnancy. Because of this, it is important to talk with your doctor or midwife about any medications you are taking, ideally before you even try to get pregnant.

If a doctor other than the one caring for your pregnancy recommends that you start a new medicine while you are pregnant, it is important that you let them know you are pregnant.

If you do need to take a new medication while pregnant, it is important to discuss the possible risks the medicine may pose on your pregnancy with your doctor or midwife. They can help you understand the benefits and the risks of taking the medicine.

Ultimately, the decision to start, stop, or change medications during pregnancy is up to you to make, along with input from your doctor or midwife. If you do take medications during pregnancy, be sure to keep track of all the medications you are taking.