Up to 85 percent of women experience morning sickness during pregnancy, and the symptoms can affect their day-to-day lives, according to the review, published Tuesday in the journal JAMA.

In the review, the researchers, led by Catherine McParlin, an associate researcher at Newcastle Upon Tyne Hospitals NHS Foundation Trust in the United Kingdom, looked at 78 studies on various treatments for nausea and vomiting during pregnancy.

Of the 78 studies, 67 were randomized clinical trials, meaning that the people in the study were randomly assigned to receive either the treatment or a placebo. Randomized clinical trials are considered the gold standard when it comes to determining if a certain treatment is effective.

However, after reviewing the studies, the researchers determined that many of them, including some of the randomized clinical trials, were "low-quality" studies, meaning that the research was imprecise, did not include a wide variety of patients, or didn`t offer enough information from which to draw conclusions, according to the study.

Overall, treatments for morning sickness fell into three main categories, according to the review. First-line treatments were those that included simple lifestyle changes, such as changes to diet, and over-the-counter remedies. Second-line treatments were medicines prescribed by a doctor, according to the review. And third-line treatments were reserved for the women with the most severe morning sickness, and are given in a hospital setting, the researchers wrote.

For women with mild morning sickness, the researchers found that consuming ginger, taking vitamin B6 supplements and using acupressure are all "appropriate initial" approaches. Acupressure is an ancient practice that involves applying pressure to certain points on the body. In the review, the researchers focused on studies that looked at applying pressure on a point on the inside of the wrist, about one-sixth of the way up the arm.

Other options, such as nerve stimulation, which involves applying a mild electrical current to certain parts of the body such as the wrist, may also be considered for mild cases, and although the procedure is safe, "the benefit is unclear," the researchers wrote. In this case, the researchers looked at a study on nerve stimulation to the same pressure point used in acupressure.

For women with mild to moderate morning sickness, or in those who`ve tried the approaches for mild morning sickness and found they didn`t work, the researchers discovered that antihistamines were associated with improved symptoms. Women are sometimes recommended to take antihistamines in combination with vitamin B6, the researchers said in their review. In the U.S., this combination is available by prescription.

Other prescription drugs, such as promethazine and metoclopramide, which affect dopamine levels in the body, were found to be helpful for women with moderate morning sickness, according to the review.

One study included in the review evaluated psychotherapy as a treatment option for women with moderate to severe morning sickness. However, the researchers concluded that evidence that it worked was not strong enough to recommend it.

Anti-nausea drugs, such as ondansetron, appeared to be beneficial for women with all levels of morning-sickness severity, the researchers wrote. The drug appears to safe for pregnant women, but more research is needed to ensure that it is safe, the researchers wrote.

For women with very severe morning sickness, corticosteroids may be used, the researchers wrote, but again, more research is needed to show that corticosteroids work as well as other medications.

The researchers noted that the findings of the review line up, for the most part, with the guidelines published by American College of Obstetricians and Gynecologist (ACOG) last year. In those guidelines, the ACOG recommended vitamin B6 or vitamin B6 plus antihistamines as a first-line treatment, ginger as a non-drug treatment and corticosteroids for severe cases that aren`t responding to other treatments.

More about: