Since marijuana doesn't benefit mother or baby it should be avoided, researchers say. But there is stronger evidence for the harms of alcohol and tobacco. Roy Morsch/Getty Images hide caption

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A New Course At Arkansas Colleges: How To Not Get Pregnant

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Acetaminophen, which is sold under the brand name Tylenol, may carry underappreciated risks. But teasing out their magnitude is a challenge. Scott Olson/Getty Images hide caption

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When Pregnant Women Need Medicine, They Encounter A Void

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Vanessa Gomez (left) with her son Ezra, 2, and her friend Cristy Fernandez with her 9-month-old-son River, in the Wynwood neighborhood of Miami. At least 14 people likely caught Zika from mosquitoes in the neighborhood, health officials say. Gomez calls that news "scary," but adds, "we cannot stop living our lives." Marta Lavandier/AP hide caption

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With Zika in Miami, What Should Pregnant Women Across The U.S. Do?

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Eight months pregnant, Mara Torres stands next to a mosquito net placed over her bed in Cali, Colombia. Health officials in Cali have delivered mosquito nets to pregnant women to help protect them from the bites of mosquitoes that can transmit dengue, chikungunya or Zika. Luis Robayo /AFP/Getty Images hide caption

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Zika Infection Late In Pregnancy Carries Little Risk of Microcephaly

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Aedes aegypti mosquito photographed through a microscope. Felipe Dana/AP hide caption

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CDC: 157 Pregnant Women In The U.S. Have Tested Positive For Zika

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In some parts of the country, this might require bug spray. Steven Errico/Getty Images hide caption

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Who Should Be Worried About Zika And What Should They Do?

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Doctors don't always suggest that pregnant women get flu shots, which may account for the relatively low vaccination rates. Jamie Grill/Tetra images RF/Getty Images hide caption

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Molecular markers show structures and cell types within a human embryo, shown here 12 days after fertilization. The epiblast, for example, appears in green. Gist Croft, Alessia Deglincerti, and Ali H. Brivanlou/The Rockefeller University hide caption

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Gist Croft, Alessia Deglincerti, and Ali H. Brivanlou/The Rockefeller University

Advance In Human Embryo Research Rekindles Ethical Debate

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Tracy Smith, 38, and her children Hazel, 8, and Finley, 5, at their home in Houston. Smith is pregnant with twins and says she's a little more worried than usual about the approach of mosquito season. Carrie Feibel/Houston Public Media hide caption

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Carrie Feibel/Houston Public Media

In Houston, Pregnant Women And Their Doctors Weigh Risks Of Zika

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