- Are of the same gender
- Have the same blood type
- Are genetically identical
- Have different fingerprints.
Mirror twins are a subset of identical twins where the twins appear to be mirror images of each other. This happens when the fertilized egg splits later than usual (7 to 12 days). Mirror twins have the same physical features but they are laterally inverted. As an example if one is right handed, the other would be left handed and so on.
If the fertilized egg splits after twelve days, it results in conjoined twins.
Dizygotic or fraternal twins: When two eggs are fertilized by two sperms and grow into two babies they are known as fraternal or two egg twins. Fraternal twins:
- May be of different genders
- Can have different blood types
- May look different from each other as other siblings do.
Some causes of multiple pregnancies may be:
- Maternal age of thirty-five or above
- History of twins on maternal side
- Use of fertility drugs or IVF treatment
- Having twins in an earlier pregnancy also increases the chances of a multiple pregnancy.
All the above is in case of fraternal twins. Monozygotic twins result from the spontaneous splitting of the fertilized egg with no apparent cause.
Multiple pregnancy is an inherently high risk pregnancy, and frequency of monitoring is higher than a singleton pregnancy. The risk of developing high blood pressure, gestational diabetes, miscarriage or birth defect is higher. It is physically more difficult than a singleton pregnancy. The belly grows faster and larger. Heartburn may begin early and continue throughout the pregnancy. Pre-term births are common in multiple pregnancies. The higher the order of multiples, the earlier is the expected birth.
Diagnosis: A multiple pregnancy diagnosis is usually done during the ultrasound when the images of more than one foetus are seen and more than one heartbeat is heard in the monitor. Physical exams, ultrasound and monitoring of the heartbeats will be done frequently to ensure the babies are developing normally.
- Do not miss the doctor’s appointment
- Avoid caffeine
- Avoid using medicines, supplements or vitamins without the doctor’s approval.
- Avoid too much physical activities
- Take adequate rest
After birth, the babies are usually lower in weight and may need to spend time in the neonatal care unit. Once home it can be an enjoyable but hectic time. With some rest, help and support from family and friends, the outcome of a multiple pregnancy can be a truly wonderful experience.