Updated on - 8 May 2026
Twin pregnancies have become increasingly common, thanks to advancements in fertility treatments and assisted reproductive techniques. Many women are opting to have children later in life, which can further increase the likelihood of having twins.
This blog explores the different kinds of twin pregnancies.
Typical & Atypical Twinning
There are typically two types of twins: fraternal and identical. Fraternal twins occur when two separate sperm fertilise two different eggs. Identical twins result from one fertilised egg splitting into two embryos.
Atypical twinning refers to rare cases in which twin conception occurs in an unusual manner. In addition to merely genetic variations, certain unusual types may have structural or developmental issues. Placental and amniotic sac sharing is another way to categorise twin pregnancies (e.g., monochorionic or dichorionic). This also aids in monitoring and identifying medical risk factors.
Types of Twins
There are two confirmed twin types in a pregnancy. These are:
Identical Twins
Monozygotic or identical twins occur when a fertilised egg splits into two embryos. They share 100% of their DNA and are usually the same gender. Identical twins can either share the same amniotic sac or have separate ones, based on when the egg divides.
Non-Identical Twins
Dizygotic or fraternal twins are the most common type. They develop when two separate eggs are fertilised by two different sperm, resulting in twins who share only 50% of their DNA. Non-identical twins can be of different genders and do not necessarily resemble each other. They usually have separate placentas and amniotic sacs.
Rare Types of Twins
While monozygotic and dizygotic twins are common, other types of twin pregnancies are:
Semi-Identical Twins
Also known as sesquizygotic twins, semi-identical twins occur when one egg is fertilised by two sperm and later divides, resulting in twins sharing both identical and fraternal genetic traits.
These twins can share anywhere from half to all of their DNA. Semi-identical twins can be of different genders.
Conjoined Twins
Conjoined twins result when a fertilised egg begins to split but does not complete the process. These twins remain physically connected and may share organs. The point of connection can vary, such as at the chest, abdomen, or head. While some conjoined twins can be separated through surgery, the procedure is complex and depends on how they are connected.
Parasitic Twins
Parasitic twins develop when one twin fails to develop fully and remains attached to the other. Unlike conjoined twins, the underdeveloped twin is not fully formed and depends on the developed twin for survival. They often appear as additional limbs or body structures on the developed twin.
Mirror Twins
A subset of identical, or monozygotic, twins; some characteristics of this sort of twins show up as mirror-like lateral reflections of one another. These could include physical traits that appear on different sides of the body, such as birthmarks. For instance, the second twin will be left-handed if the first twin is right-handed.
Conclusion
The pregnancy phase is fascinating, whether you are expecting a singleton or twins. However, alongside the excitement, it's important to be prepared for any sudden mishaps. This is where comprehensive maternity insurance comes into play. Having the right health insurance policy can help alleviate concerns by covering medical expenses before and after delivery.
FAQs
1. How common are twin pregnancies?
Twin pregnancies are relatively uncommon in naturally occurring pregnancies. Though with fertility treatments and later maternal age, the overall rate has increased nowadays. In India, twin births are still considered rare, though urban areas with greater access to fertility treatments may have slightly higher rates.
2. Does having twins increase medical expenses significantly?
Twin pregnancies often involve more frequent check-ups, specialised care, and more chances of needing NICU (neonatal intensive care unit) support after delivery. These lead to additional medical expenses. Purchasing a suitable health insurance plan with maternity coverage can help manage these additional costs.
3. Can lifestyle or genetics influence the chances of having twins?
Yes. Certain factors, like family history, especially on the mother’s side, maternal age, and fertility treatments, can increase the likelihood of conceiving twins.
Disclaimer: The information provided in this blog is for educational and informational purposes only. It is not intended as a substitute for professional advice, diagnosis or treatment. Please consult a certified medical and/or nutrition professional for any questions. Relying on any information provided in this blog is solely at your own risk, and ICICI Lombard is not responsible for any effects or consequences resulting from the use of the information shared.