Transcript for Kate Middleton's Illness Sparks Twins Speculation
For more, now, on why kate is in the hospital. The duchess is dealing with hyperempha hyperemesis, which is extreme morning sickness. Sharyn alfonsi went through the same condition in both her pregnancies. Reporter: Not once, but twice. It sounds miserable. Reporter: It's tough. People talk about morning sickness. You're sick in the morning, the afternoon, the night. Morning sickness, you get sick in the morning a couple times. I was sick a dozen times a day. Two dozen times a day at the worst. And you end up on an i.V. Because you can't get the nutrients you need. You can't keep food down. It's scary. You actually fainted a couple times. Reporter: I fainted a couple times. You can't eat. You try to eat and drink stuff. You can't keep anything down. Even prenatal vitamins. You take a prenatal vitamin. You can't keep that down. And I kept thinking that down. If I would keep this down for a second, the baby will get what it needs. And ultimately, you endp on an i.V. At what stage in your pregnancy did it begin? Reporter: I feel like two seconds after I got pregnant. I don't think that's correct. For me, it started about two months. And it lasted, with my son, until I was six or seven months. And with my daughter, even longer. Oh, my goodness. George, you were telling me, ali had it. Ali's began when she was six to eight weeks pregnant? Right with ellie, our first daughter, the i.V., The same thing. The hospital, the whole thing. With harper, our second daughter, it wasn't quite as bad. But she tried everything. Acupuncture, all kinds of treatments. Nothing works. All of your well-meaning friends say, try sucking on a lemon. Acupuncture. Let them do it. You let them do it? I was willing to try it. Now, I'm afraid of murphy's oil. I have an aversion to that. But none of that stuff worked. You know? And saying the saltines and ging ginger ale, it's a different level. We saw kate playing hockey a couple of days ago. I saw you working throughout your pregnancy. How do we see her video functioning normally and now, two days later, in the hospital? It can turn that quickly. I remember knowing where every trash can was, just in case. And she will probably have those eyes for her pregnancy. Sharyn, thanks for the details.
This transcript has been automatically generated and may not be 100% accurate.