There’s currently no evidence the novel coronavirus can pass from a mother to a child in the womb, according to a study published Wednesday in the medical journal The Lancet.

The small, observational study included nine women in Wuhan, China, in their third trimesters of pregnancy. Each woman had a lab-confirmed case of novel coronavirus pneumonia, officially called COVID-19, and was treated from January 20 through January 31.

Researchers tested amniotic fluid, cord blood and neonatal throat swabs at birth to study the possibility of fetal infection with the novel coronavirus, and all the samples tested negative. All the women had cesarean sections, so it’s not clear if the virus could be passed from mother to child during vaginal birth.

All the pregnancies resulted in live births and none of the infants required special pediatric treatment. Four of the mothers experienced preterm labor, but the researchers said the causes weren’t related to coronavirus. Pregnancy complications that appeared after the illness began included fetal distress in two cases and premature rupture of membranes in two cases.

The study also found that none of the pregnant women developed severe pneumonia or died as of February 4. Their symptoms, including fever, cough, sore throat and muscle aches, were similar to symptoms in people who aren’t pregnant.

Why this is important: This is notable because pregnant women are particularly susceptible to respiratory pathogens and severe pneumonia, the researchers wrote. One study found about half the pregnant women who developed SARS during that outbreak were admitted to the intensive care unit, and during the H1N1 flu pandemic, pregnant women were more likely than the general population to be admitted to the hospital and were at increased risk of complications, the researchers wrote.

Still, researchers said, the case of an infant who tested positive for the coronavirus within 36 hours of birth in early February means special consideration is needed to keep newborns safe if their mothers are infected with the coronavirus.

It’s also not clear how the novel coronavirus could affect a fetus in the first or second trimester of pregnancy, the researchers wrote.