Types of Twin Pregnancies

I recently saw a young lady with no history of twins in the family thoroughly shocked but overjoyed (and maybe overwhelmed) when I told her she had twins. She was in her early pregnancy at 8 weeks. An ultrasound scan showed two distinct waterbags and two foetal echoes with heartbeats. This was a non-identical twin pregnancy which is more common than identical twins. It results from the fertilisation of two separate eggs that is released from the ovary. The incidence of twin pregnancies is 1% of which 2/3rds will be non identical and 1/3rd identical.
 Identical twins result from the splitting of the zygote after the egg and sperm have fused. There are two types of identical twins, one of which has two separate placentas and the other type has one single placenta. The types of identical twins is determined by the time at which cleavage of the zygote takes place. If before 4 days, the dichorionic diamniotic DC DA twin with two placentas is formed. This accounts for 25% identical twins. If between 4 and 8 days, the monochorionic diamniotic MC DA twin with a single placenta forms. This is the most common accounting for 75% identical twins. If cleavage takes place between 8 and 12 days, the monochorionic monamniotic MC MA twin with a single placenta occurs. This rare at less than 1%. Cleavge after 12 days may result in conjoined twins.
The importance of knowing which type of twin pregnancy lies in the complication rates. The MC MA twin unfortunately has an 85% chance of mortality mostly due to cord entanglement. The MC DA and DC DA have complications mainly resulting from twin-twin transfusion, and intra-uterine growth retardation resulting from the stronger twin drawing more nutrition and depriving the other. So as an obstetrician it is not always `joyful' to see a twin pregnancy and we have to be extra vigilant in the obstetric care of the patient.

Pregnancy and vitamin D deficiency

It is not widely known but vitamin D deficiency is associated with increased risk of pregnancy complications. Although there is no need to do vitamin D levels on every patient, it is prudent for all pregnant women to ensure that their diet is rich in vitamin D. Low levels are associated with gestational diabetes, pre-eclampsia, low birth weight babies, bacterial vaginosis. Vitamin D is obtained from sun exposure. However in Asia we tend not to like going out in the sun unlike westerners. Some sun exposure would be good for a pregnant woman. Other sources of vitamin D include foods such as oily fish rich in omega 3 wild salmon, a certain amount from meats such as chicken, beef and eggs. Vitamin D supplementation is usually not necessary unless there is a history of vitamin D deficiency. Excess vitamin D intake (more than 10,000 IU/day) in the form of supplements can lead to toxicity causing foetal abnormalities, kidney stones.

http://www.medpagetoday.com/OBGYN/Pregnancy/38113

Repeat caesarean section or vaginal birth

In a recent large study from the University of Adelaide, it was found that risks to both baby and mother were significantly lower if a mother has an elective caesarean section after a previous caesarean section compared with a vaginal birth. The risks for serious complications and death for baby was 2.4% for attempted vaginal birth and 0.9% after elective caesaean section. The risks for serious complications and death for mother was also also significant eg the risk of life threatening bleeding was 2.3% after vaginal birth and 0.8% after elective caesaean section.
This is one more study that shows that the idict, "once a caesarean section always a caeasean section" may be the wiser choice.
http://www.sciencedaily.com/releases/2012/03/120313185229.htm

Obesity in pregnancy

Most women know that smoking and drinking don't go with pregnancy and automatically will reduce or stop before getting pregnant. However few know that obesity and extreme underweight carry just as much risk if not more. Obesity may not be so common in the local context but I am increasingly seeing this as our foreign population in Singapore rises. Obesity is associated with hypertension, diabetes, beta streptococcal infection, large babies, premature labour, stilbirths, higher chance of caesarean section, greater risks than normal from caesarean section complications, postnatal depression. So counselling for those over and underweight should be part of the preconception consultation

Premature Labour

Although uncommon, there are certain factors that can bring about premature labour (defined as labour before 37 weeks gestation). The most common being a defect in hormonal production resulting in low or subnormal progesterone levels. A congenitally short cervix ( length 10-20mm) is also a factor and recent studies have shown that vaginal progesterone given throughout the pregnancy helps to delay the onset of labour. Other factors such as multiple pregnancy, multipara, inadequate nutrition, low lying placenta, medical conditions such as asthma, diabetes all predispose to premature labour. Those who have a threatened miscarriage in the early pregnancy are also at greater risk of premature labour and a case can be made for administering progesterone throughout the pregnancy in such cases

Failed contraceptive and pregnancy

I had a patient who recently conceived after taking oral contraceptives. The failure rate is very low in the order of 0.01% but it does happen. One has to be careful and counsel that sometimes this can happen when one just starts taking the oral contraceptive pill and that certain antibiotics taken together with OCs can lower it's effectiveness. The dilemma is whether the pill will have any effect on the pregnancy. OCs are a category C drug ie it has shown to have effects on animals and on humans. It has been shown to have virilising effects on a female foetus. However one should not jump straight to having an abortion, as the findings are sporadic and there are many women who have taken progestogens in pregnancy without any effect on the foetus. One has to consider the effects of an abortion and weigh the risks viz. damage to the cervix, damage to the lining of the womb, infection and blockage of the tubes, against the risks of a virilising effect on the foetus.The patient has decided to continue with the pregnancy and in my opinion this was the wiser decision.

Is preeclampsia in pregnancy preventable?

A few days ago I had to do a caesarean section for a young lady in her first pregnancy. She was only 28 weeks into her pregnancy. Unfortunately she had developed severe preeclampsia, a condition of the placenta characterised by high blood pressure, swelling and protien in the urine. She had underlying essential hypertension which was probably inherited and subsequently developed this condition. As her blood pressure became uncontrollable despite all medications, I made the decision to deliver her as it would otherwise have endangered her life and that of her baby.

There have been many proposals put forward over the years to prevent this condition but none proven. These include, a high protein diet but the World Health Authority concluded that in the abscence of a deficiency it would not be of benefit. Fish oil supplementation once proposed but subsequent trials have shown no benefit. There are more ongoing studies in New Zealand and Scandinavia. Calcium supplementation was shown initially to have some benefit in small trials but a large trial published by the New England Journal showed that there was no benefit in 1997. Low dose aspirin has been shown to have some benefit in those who have had previously had a pregnancy with preeclampsia and at risk in subsequent pregnancies so this may be of benefit but only on hindsight. The most recent study by the British Medical Journal showed that high doses of L-arginine together with anti-oxidants are of benefit but further studies need to be done.

www.eurekalert.org/pub_releases/2011-05/bmj-nss051811.php