Double Joy, Double Trouble?



The occurrence of identical twins after a single embryo transfer

Even after many years of being a doctor, it still brings me immense joy to announce to my patient that she is indeed pregnant following a successful infertility treatment. And sometimes, the happiness is multiplied, as there isn’t one, but two buns in the oven!


In general, it is widely known that the occurrence of multiple births is much higher following assisted reproductive technologies (ART) as compared to incidences of twins in natural or spontaneous pregnancies. This is directly related to the number of embryos transferred back to the uterus. In general, if 2 embryos are transferred back into the uterus, the chance of having twin pregnancies is around 20-30%. As we all know, twin pregnancies carries more risks to the expecting mother as well as the babies. The risks of miscarriage, bleeding in pregnancy, high blood pressure, diabetes in pregnancy, Placenta Praevias, Caesarean Sections are some of the significant obstetric risks. The babies are also at risk of preterm births, stillbirths and complications associated with preterm deliveries such as cerebral palsies.


Therefore, in many countries especially in the west, it is mandatory that the patients are informed of these risks before an embryo transfer. Some countries had restricted the number of embryos transferred to one. This move had significantly reduce the incidence of twins following an IVF and had reduced the economic burden associated with medical care of pregnancies associated with twins


However, in recent years, it had been reported that there is a higher incidence of identical twins following single embryo transfer.


While the incidence of fraternal twins following the transfer of two embryos is an easily understandable consequence of IVF, the causes for identical twins after ART remain speculative at best. However, there is some evidence that attributes the phenomenon to the micromanipulation techniques, length of culture and culture medium used during treatment, as well as the genetics of the parents.

Identical twins, also known as monozygotic twinning or MZT, occur when an egg and a sperm unite to form a single zygote that divides into two embryos or separate individuals. It is a rare phenomenon, which occurs in only about 1% of natural conceptions. However, in assisted conceptions, the occurrence of monozygotic twinning almost doubles.


The splitting of the zygote into separate embryos can occur at any time during the first 2 weeks after fertilisation. However, the timing of the split will influence the type of identical twin. For example, in around 1/3 of MZT cases where the split occurs within 72 hours of fertilisation, the result is two placentas and two amniotic sacs. In the remaining 2/3 of MZT cases, the splitting occurs 4-8 days after fertilisation, resulting in one placenta and two amniotic sacs. And in about 5% of MZT cases, where splitting occurs 8-13 days after fertilisation, the outcome is one placenta and one amniotic sac. In very rare cases, the outcome is conjoined twins.


Although the prospect of having twins is certainly exciting, couples must also understand that twin pregnancies are considered high risk. They can lead to various pregnancy complications with long-lasting and even permanent effects for the children. These include caesarean section, premature birth, low birth weight, Twin-Twin Transfusion Syndrome (TTTS), pre-eclampsia, gestational diabetes, fetal abnormalities and congenital abnomalies. In view of the complications that can arise from a twin pregnancy, do speak to your infertility consultant about the risks involved should you have any worries.



Doctor, twins please!!!!


As a mother of a pair of twins, my patients are usually quite curious how I managed to conceive with a pair of twins. Most of them thought that I have been through an IVF myself.

However, the reality is that I did not need to do so. I came from a family blessed with many pairs of twins and there were even triplets (conceived naturally) in my family. Multiple pregnancies gene runs in my father’s family: My 5th & 6th uncles are twins, my 5th uncle went on having a pair of twin girls himself. My first uncle had triplets (conceived naturally) in addition to 6 other children he had (with just one wife, blessed). Nobody suspected that my aunt carried triplets until the second baby was born and the doctor found another baby in the womb. Of course we can’t criticize the doctors then because those days were the days before the advent of ultrasound scans and the use of ultrasound scans for pregnancy only came on 10-15 years later. My first aunt (my father’s only sister) have a pair of twin grand-daughters. If you search long and hard enough, and look thoroughly at my family tree, you will notice that my grandfather’s brothers and sisters are all blessed with twins in their family. If you take all these pairs of twins into consideration, you are talking about probably at least 10-15 pairs of twins in the lineage of my great-grandfather.

How did it happened? We have no idea. We used to think that one would inherit the multiple pregnancy genes through maternal lineage. However, my father’s family had challenged the popular belief. My father used to think that it was the water or the soil around the area where they lived. However, I don’t live near the area where the family came from and I don’t believe that my brief stays of 1-2 weeks yearly as a child at my ancestor home would have contributed to the incidence. My aunt who delivered the triplets did not live around the ancestor home either.

My interesting family history has pre-determined my destiny to be blessed with a pair of twins. And as I am blessed with a job of my dream to help to create babies in the field of Assisted Reproductive Medicine, my profile as a mother of twins has gradually become a fascination for my patients.

I have had many e mails from patients directed to me asking whether I could help them to conceive with a pair of twins.

I felt very privileged by their request but yet find this request daunting because even with all the Fertility Treatment which are available, there is still no guarantee that one could be pregnant with twins.

The incidence of twins is 1:80 pregnancies if you let nature run its course. If a woman takes Fertility pills such as Clomid (Clomiphene citrate) to enhance their fertility, the chance of conceiving a pair of twins is estimated to be around 5-10% if she fall pregnant. If she undergo ovulation stimulation coupled with an intra-uterine insemination (IUI), the chance of her pregnant with a pair of twins is around 10-15%. If she undergo In-vitro Fertilization (IVF), her chance of getting a pair of twins is around 20% if she have had 2 embryos replaced into her womb.

What patient needs to understand is that all Fertility Treatments increase the chance of having multiple pregnancies in different proportions but none will be able to guarantee the outcome.

Having twins is not without its complications. I always like to warn patients but I am not sure whether this goes down well with them. These complications are real but yet we as clinicians find it hard to present it to patients simply because it is not so palatable.

First and foremost, multiple pregnancy poses risk for the expecting mother. There are increased risk of complications such as:
(1) high blood pressure in pregnancy (I was a typical example of such complications, having had fulminant high blood pressure with presence of protein in my urine and required high dependency care and emergency Caesarean section at 33 weeks)
(2) High blood sugar in pregnancy (I escaped narrowly as my test result was near borderline)
(3) Low lying placenta or Placenta Praevia in pregnancy (That too was a concern until 28 weeks and my obstetrician, who happened to be my boss ordered me to stop work at 26 weeks)
(4) preterm delivery (Statistically, 60% of twins are born before 37 weeks. Some of the pre-term deliveries were attributed by the medical conditions in pregnancies which required early delivery)

(5) Anaemia in pregnancy

The risks for the babies include:

(1) Higher risk of miscarriage & stillbirth

(2) Higher risk of early neonatal loss. The risk of death for premature babies around the week of birth is five times higher for twins and nine times higher for triplets than single babies.

(3) Higher risk of prematurity and long stay in Neonatal Intensive Care Unit, half of all twins are born prematurely (before 37 weeks) and have a low birthweight of under 2.5kg (5.5lb); triplets have a 90% chance of being born prematurely and of having a low birthweight. My babies was taken to Neonatal ICu at birth and stayed for 16 days. It was the worst 2 weeks of of my life, having to go through the emotional roller costers for 2 weeks

(4) Higher risk of babies having Cerebral Palsy. Twins are four times and triplets 18 times more likely to have cerebral palsy than single babies.

As for the family, the burden would be:

(1) $$$ (Diapers , Milk Powder, and everything else that requires 2 sets at the same time)

(2) Childcare. Looking after a pair of twins who cried simultaneously, need feeding and changing simultaneously would drive a sane woman insane.

(3) Lack of ZZZZ. A chronic problem as you need to wake up more often in the middle of the night for feeding and changing the diapers

(4) Bigger car required. A MPV is required to fit in 2 car seats and a spacious boot to fit in a double baby prem

So, before you ask me to help you to conceive with a pair of twins, would you consider reading this article beforehand?