Incomplete Development in a Twin Pregnancy at 9 Weeks

Regarding fetal developmental abnormalities at 9 weeks?

Hello Doctor: Previously, an ultrasound showed that I was having twins, and there were heartbeats.
However, at a larger hospital during the 9-week mark, it was found that one baby was developing healthily, with a clear view of the head, brain, and limbs, while the other was getting smaller and the doctor informed me that its development was incomplete, including the brain.
I would like to ask if the underdeveloped baby has no chance of normal growth anymore, or is there still a possibility for it to continue developing? Currently, I am waiting, and if the baby is not healthy, I plan to let it naturally resorb.
Will this affect the healthy baby? (dizygotic twins) Additionally, if the unhealthy baby does not gradually resorb, what should I do? The doctor mentioned that it is currently not suitable to intervene, as it may affect the healthy baby.

11, 30~39 year old female. Ask Date: 2020/01/08

Dr. Cao Guotao reply Obstetrics and Gynecology

Hello, if there is another underdeveloped condition, we can only observe it.
If it resolves on its own, it generally will not affect the normal fetus.
However, we can only monitor and track it, as there is no specific treatment available.
Wishing you good health.

Reply Date: 2020/01/08

More Info

In a twin pregnancy, especially when one fetus shows signs of incomplete development, it can be a concerning situation for expectant parents. At 9 weeks gestation, the development of the embryos is still in its early stages, and various factors can influence their growth. The situation you described, where one twin is developing normally while the other is not, is known as "vanishing twin syndrome." This phenomenon occurs when one of the embryos in a multiple pregnancy fails to develop properly and is eventually reabsorbed by the body.

Regarding your specific questions:
1. Possibility of Continued Development: If one twin is showing signs of incomplete development, it is often unlikely that it will continue to develop normally. The chances of a non-viable twin recovering and developing healthily decrease significantly as the pregnancy progresses. However, each case is unique, and there are rare instances where a twin may show improvement. Continuous monitoring through ultrasounds is essential to assess the situation.

2. Impact on the Healthy Twin: Generally, if one twin is not developing properly, it should not adversely affect the healthy twin. The placenta typically provides adequate support to the viable fetus, and the body can often manage the situation without significant complications. However, there are exceptions, such as if the pregnancy is complicated by shared placental circulation, which can lead to conditions like Twin-to-Twin Transfusion Syndrome (TTTS). In your case, since you mentioned that the twins are fraternal (dizygotic), the risk of complications affecting the healthy twin is lower.

3. Management of the Non-viable Twin: If the non-viable twin does not naturally resorb, the medical team will likely continue to monitor the situation closely. In many cases, doctors will recommend a conservative approach, allowing nature to take its course. Surgical intervention is typically avoided unless there are significant risks to the healthy twin or the mother’s health. If the non-viable twin remains present without causing complications, it may simply be monitored until delivery.

4. Follow-up Care: Regular follow-up appointments with your healthcare provider are crucial. They will perform ultrasounds to monitor the growth and health of both fetuses. If there are any signs of distress in the healthy twin or if the situation changes, your doctor will discuss the best course of action.

5. Emotional Support: It’s important to acknowledge the emotional toll that such situations can take on expectant parents. Seeking support from family, friends, or professional counselors can be beneficial in navigating the complexities of a twin pregnancy, especially when facing uncertainties.

In conclusion, while the situation can be distressing, it is essential to remain in close contact with your healthcare provider, who can provide personalized guidance based on the ongoing assessments of your pregnancy. Each pregnancy is unique, and the medical team will be best equipped to advise you on the safest and most appropriate actions to take moving forward.

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