--- title: What Is Hyperemesis Gravidarum? description: Kate Middleton is suffering from a severe form of morning sickness called hyperemesis gravidarum. Here's what that is. canonical: https://time.com/4926496/kate-middleton-hyperemesis-gravidarum/ author: Mahita Gajanan article:opinion: false article:content_tier: free article:published_time: 2017-09-04T14:23:41.000Z article:modified_time: 2026-02-23T17:16:13.937Z article:section: Health og:title: Kate Middleton Is Suffering From Hyperemesis Gravidarum. What Is That? og:description: As the princess is expecting her third child og:url: https://time.com/4926496/kate-middleton-hyperemesis-gravidarum/ og:site_name: TIME og:image: https://static.time.com/v3/assets/bltea6093859af6183b/blta6298ca0e6ca89e4/6988dc4ecf40a83933c493b2/kate-middleton-morning-sickness.jpg?branch=production&width=1200&quality=75&auto=webp&crop=16:9 og:image:width: 1795 og:image:height: 1010 og:image:alt: The Duke And Duchess Of Cambridge And Prince Harry Visit The White Garden In Kensington Palace og:type: article twitter:card: summary_large_image twitter:title: Kate Middleton Is Suffering From Hyperemesis Gravidarum. What Is That? twitter:description: As the princess is expecting her third child twitter:image: https://static.time.com/v3/assets/bltea6093859af6183b/blta6298ca0e6ca89e4/6988dc4ecf40a83933c493b2/kate-middleton-morning-sickness.jpg?branch=production&width=1200&quality=75&auto=webp&crop=16:9 ---  # Kate Middleton Is Suffering From Hyperemesis Gravidarum. 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Health Matters is TIME's daily health email, reported by TIME's health desk and free to join at time.com/newsletters. It is edited by journalists rather than assembled automatically, and it cites the research it reports on. #### Is Health Matters free? Yes. Health Matters is a free daily newsletter from TIME, available at time.com/newsletters. #### Who reads TIME's Health Matters newsletter? Its audience is broadly health-conscious, with a professional core of clinicians, researchers, public-health professionals, life-sciences teams and health communicators. by [Mahita Gajanan](https://time.com/author/mahita-gajanan/) ## Mahita Gajanan Gajanan is an editor at TIME. Sep 4, 2017 2:23 PM UTC  Catherine, Duchess of Cambridge visits the Sunken Garden in the grounds of Kensington Palace on August 30, 2017 in London, England. Catherine, Duchess of Cambridge visits the Sunken Garden in the grounds of Kensington Palace on August 30, 2017 in London, England. Max Mumby/Indigo--Getty Images by [Mahita Gajanan](https://time.com/author/mahita-gajanan/) ## Mahita Gajanan Gajanan is an editor at TIME. Sep 4, 2017 2:23 PM UTC Kate Middleton, also called the Duchess of Cambridge, is [pregnant with her third child](http://time.com/4926420/prince-william-kate-pregnant-third-child/), Kensington Palace said Monday. Middleton and her husband, Prince William, Duke of Cambridge, have not yet revealed a due date for the child. As with her previous two pregnancies, Middleton is suffering from a [severe form of morning sickness](http://time.com/4926420/prince-william-kate-pregnant-third-child/) called hyperemesis gravidarum, which prevented her from attending engagements on Monday. The illness sent Middleton to the hospital during her first pregnancy and recurred during her second pregnancy as well. According to a [TIME report on the condition](http://time.com/3303811/kate-middleton-pregnant-morning-sickness/), having hyperemesis gravidarum once increases its chances of cropping up again: --- > “” --- The condition can be caused by hormonal changes that take place during the first trimester of pregnancy, including the steep rise of human chorionic gonadotropin, which the placenta releases as it prepares to nourish the fetus. ```json [{"@context":"https://schema.org","@type":"NewsArticle","@id":"https://time.com/4926496/kate-middleton-hyperemesis-gravidarum/","mainEntityOfPage":{"@type":"WebPage","@id":"https://time.com/4926496/kate-middleton-hyperemesis-gravidarum/"},"headline":"Kate Middleton Is Suffering From Hyperemesis Gravidarum. 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