Rh Factor in Pregnancy: Key Considerations for Couples

Rh-negative & Rh-positive

Dear Dr.
Lu,
I am blood type O negative, and my husband is blood type O positive.
We plan to conceive in late November this year.
I previously had a pregnancy where the fertilized egg implanted at the opening of the fallopian tube, and at that time, we did not intend to have a child so early, so we opted for an abortion.
May I ask, in this upcoming pregnancy, would this be considered my first or second pregnancy? (I have heard that when an RH negative and an RH positive person marry, special attention is needed during the second pregnancy, but I am unclear about what to watch for… I apologize.) If this upcoming pregnancy is considered my second, what precautions should I take? Will I need to receive any injections? (We plan to have two children.)
Additionally, could you explain what causes a fertilized egg to implant at the opening of the fallopian tube rather than in the uterus? If I have experienced implantation at the fallopian tube before, will it happen again in the future? If the fertilized egg does not implant in the normal location—the uterus—what effects could this have on the mother and the fetus? I am very worried and scared… Please help clarify these concerns for me.
Thank you very much!
Sincerely,
Xiao Mei
October 6, 2003

Xiao Mei, 20~29 year old female. Ask Date: 2003/10/06

Dr. Lü Lizheng reply Obstetrics and Gynecology

Hello! If a fertilized egg implants in an abnormal location (outside the uterine cavity), we refer to this as an ectopic pregnancy, which can occur in the fallopian tubes, cervix, or at the exit of the fallopian tubes.
This condition typically causes bleeding, including internal bleeding, and often requires surgical intervention.
Currently, there are two hypotheses regarding the causes of ectopic pregnancies: the first suggests that the embryo itself has defects, while the second posits that the implantation site is inherently compromised.
The recurrence rate for ectopic pregnancies is approximately 5%.
However, there is some skepticism regarding whether an ectopic pregnancy at the fallopian tube exit can be effectively managed through standard miscarriage procedures, as ultrasound may reveal the embryo is very close to the fallopian tube exit but still within the uterine cavity.

If you successfully conceive again, your fetus will be Rh-positive while you are Rh-negative.
Consequently, during birth, some of the fetal blood may flow back into your circulation, prompting your body to produce antibodies against the Rh factor.
This will not affect your health, but it could lead to complications such as miscarriage or stillbirth in subsequent pregnancies.
Therefore, it is advisable to test for the presence of Rh antibodies before pregnancy.
Additionally, shortly after delivery, receiving an injection of Rh immunoglobulin can help prevent the development of an immune response and protect future pregnancies.
Best wishes for your health,
Dr.
Lu Li-Cheng, Director of Obstetrics and Gynecology, Taoyuan Hospital, Department of Health, Executive Yuan.

Reply Date: 2003/10/06

More Info

Understanding the Rh factor in pregnancy is crucial for couples, especially when one partner is Rh-negative and the other is Rh-positive. In your case, you are O Rh-negative, and your husband is O Rh-positive. This combination can lead to specific considerations during pregnancy, particularly regarding the potential for Rh incompatibility.

First Pregnancy vs. Second Pregnancy
Regarding your question about whether this upcoming pregnancy is considered your first or second, it is generally classified as your second pregnancy. The previous pregnancy, despite ending in an ectopic pregnancy (where the fertilized egg implants outside the uterus), is still counted as a pregnancy.

Rh Factor Considerations
When an Rh-negative mother carries an Rh-positive baby, there is a risk that the mother's immune system may produce antibodies against the Rh factor if fetal blood cells enter her circulation. This can happen during delivery or if there is any bleeding during pregnancy. If the mother develops these antibodies, it can lead to complications in future pregnancies, such as hemolytic disease of the newborn (HDN), where the mother's antibodies attack the baby's red blood cells.

To prevent this, it is standard practice for Rh-negative mothers to receive an injection of Rh immunoglobulin (RhoGAM) around the 28th week of pregnancy and within 72 hours after delivery if the baby is Rh-positive. This injection helps prevent the mother from developing antibodies against the Rh factor.

Ectopic Pregnancy Concerns
You mentioned a previous ectopic pregnancy, which occurs when a fertilized egg implants outside the uterus, commonly in the fallopian tubes. The reasons for ectopic pregnancies can include:
1. Previous Pelvic Inflammatory Disease (PID): This can cause scarring in the fallopian tubes.

2. Endometriosis: This condition can affect the normal functioning of the reproductive organs.

3. Tubal Surgery: Any previous surgery on the fallopian tubes can increase the risk.

4. Contraceptive Methods: Certain methods, like IUDs, can increase the risk of ectopic pregnancies.

Having had one ectopic pregnancy does increase the risk of having another, but it is not guaranteed. The recurrence rate is about 5-15%. If you have concerns about the risk of another ectopic pregnancy, it is essential to discuss this with your healthcare provider, who may recommend monitoring your early pregnancy with ultrasounds to ensure proper implantation.

Implications of Ectopic Pregnancy
If a fertilized egg does not implant in the uterus, it can lead to serious health risks for the mother, including internal bleeding, which can be life-threatening. Therefore, it is crucial to seek medical attention if you experience symptoms such as severe abdominal pain, dizziness, or abnormal bleeding.

Conclusion
In summary, as you prepare for your upcoming pregnancy, it is essential to be aware of the implications of being Rh-negative and to take preventive measures against Rh incompatibility. Additionally, keep in mind the risks associated with a history of ectopic pregnancy. Regular prenatal care and open communication with your healthcare provider will be vital in ensuring a healthy pregnancy. If you have any further questions or concerns, do not hesitate to reach out to your doctor for personalized advice and support.

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