- With Mayo Clinic obstetrician and medical editor-in-chief
Roger W. Harms, M.D.
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Roger W. Harms, M.D.
Roger W. Harms, M.D.
"Nothing helps people stay healthy more than the power of real knowledge about health." — Dr. Roger Harms
As medical editor-in-chief, Dr. Roger Harms is excited about the potential for MayoClinic.com to help educate people about their health and provide them the tools and information to live healthier lives.
The Auburn, Neb., native has been with Mayo Clinic since 1981 and is board certified in obstetrics and gynecology. Dr. Harms is a consultant and associate professor of obstetrics and gynecology, and his specialty areas include office gynecology, high-risk obstetrics and obstetrical ultrasound.
From 2002 to 2007, Dr. Harms was director for education for Mayo Clinic, Rochester, Minn. Dr. Harms was the 1988 Mayo Medical School Teacher of the Year and served as associate dean for student affairs and academic affairs before taking this leadership role. He is the co-author of the "Mayo Clinic Model of Education." In 2008, Dr. Harms was presented the Distinguished Educator Award, Mayo Clinic, Rochester.
Dr. Harms is vice chair of the Department of Obstetrics & Gynecology and medical editor of the Pregnancy section on this Web site. In addition, Dr. Harms is editor-in-chief of the "Mayo Clinic Guide to a Healthy Pregnancy" book, a month-by-month guide to everything a woman needs to know about having a baby.
"My medical education experience has grown out of a love of teaching, and that is what this site is about," Dr. Harms says. "If any visitor to this site makes a more informed and thus more comfortable decision about his or her health because of the information we provide, we are successful."
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Question
Rh factor in pregnancy: When is it a problem?
I'm pregnant. What do I need to know about Rh factor or Rh incompatibility?
Answer
from Roger W. Harms, M.D.
Rhesus (Rh) factor is an inherited trait that refers to a specific protein on the surface of red blood cells. If your blood has the protein, you're Rh positive — the most common Rh factor. If your blood lacks the protein, you're Rh negative. Your health care provider can determine your Rh factor with a basic blood test. Your Rh factor doesn't affect your health. However, your pregnancy needs special care if you're Rh negative and your partner is Rh positive.
During pregnancy — or, more likely, during delivery — your blood and the baby's blood may mix. If you're Rh negative and your baby is Rh positive, your body may produce Rh antibodies to fight the baby's blood. The antibodies are generally harmless during the first pregnancy. However, if you have a subsequent pregnancy with an Rh positive baby, your Rh antibodies may attack the baby's red blood cells. The subsequent Rh positive baby may develop Rh disease, a life-threatening condition that could require a blood transfusion through the umbilical cord during pregnancy or immediately after delivery.
If you're Rh negative, your health care provider will likely give you an Rh immune globulin injection at about 28 weeks into your first pregnancy. You'll need another Rh immune globulin injection shortly after delivery if the baby is Rh positive. The Rh immune globulin blocks your body's recognition of Rh positive cells, which prevents any problems with Rh incompatibility. An Rh immune globulin injection may be needed in other cases as well, such as after an episode of vaginal bleeding, an amniocentesis, an ectopic pregnancy or a miscarriage.
If you're Rh negative, you'll likely need an Rh immune globulin injection during any subsequent pregnancies and after the delivery of each Rh positive baby as well.
| Mother's Rh factor | Father's Rh factor | Baby's Rh factor | Precautions |
|---|---|---|---|
| Rh positive | Rh positive | Rh positive | None |
| Rh negative | Rh negative | Rh negative | None |
| Rh positive | Rh negative | Could be Rh positive or Rh negative | None |
| Rh negative | Rh positive | Could be Rh positive or Rh negative | Rh immune globulin injections |
If you're Rh negative, remind your health care team of your Rh status when you seek medical care during pregnancy.
Next questionBlighted ovum: What causes it?
- Moise KJ. Management of rhesus alloimmunization in pregnancy. Obstetrics and Gynecology. 2008;112:164.
- Moise KJ. Management of rhesus (Rh) alloimmunization in pregnancy. http://www.uptodate.com/home/index.html. Feb. 19, 2009.
- Moise KJ. Pathogenesis and prenatal diagnosis of rhesus (Rh) alloimmunization. http://www.uptodate.com/home/index.html. Feb. 19, 2009.
- Moise KJ. Prevention of rhesus (Rh) alloimmunization. http://www.uptodate.com/home/index.html. Feb. 19, 2009.
- McInerny TK, ed. American Academy of Pediatrics Textbook of Pediatric Care. Elk Grove Village, Ill.: American Academy of Pediatrics; 2009:941.
