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Monday, 26 August 2013

Hypothyroidism in Pregnancy

This condition is important to diagnose early in the pregnancy, and ideally before pregnancy begins. Even a mildly underactive thyroid may lead to conditions which affect the baby's brain development. It has been shown that low levels particularly those in the lower 5th percentile may lead to lower IQ's and autism.
Anyone with symptoms or a family history of Hashimoto's Disease ( an autoimmune disorder of the thyroid) should be treated before getting pregnant. I recently had a patient in her early pregnancy with this condition. She had been rightly treated by her GP with replacement therapy. However it is also important to have regular blood tests to monitor the thyroid levels as too high a thyroid hormone level may result in its own set of complications. The best tests would be the T4 and TSH, the latter of which should be kept to <2mIU/ml.
An underactive thyroid may be caused by a lack of iodine in the diet. Selenium taken before pregnancy may help in those who have mild hypothyoidism.

Monday, 8 April 2013

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.

Thursday, 28 March 2013

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.