Thursday, 2 June 2011

The early pregnancy. Environmental factors and foetal abnormalities

Q  Why is smoking in pregnancy bad?

The chance of a normal pregnancy outcome is reduced as complications are increased by the reduction in blood flow caused by nicotine to the foetus. Miscarriages, growth retardation, decreased birth weight, intra-uterine death and prematurity are some of the complications.

Q  There are several smokers in my workplace. Will inhalation of cigarette smoke affect my baby. It has been shown that in fact inhalation of secondary smoke is even more potent to your foetus and may cause all the complications of smoking. It is important to try and avoid this as far as possible.

Q  Is consuming alcohol harmful during pregnancy?

The effect of alcohol depends on the amount you drink. Generally you should not exceed a glass of wine a week. Heavy drinking (>6 glasses) can cause foetal alcohol syndrome in as many as 50% pregnancies. This is characterised by low birth weight, a small head, abnormal features of the face and head, mental retardation and abnormal coordination with delayed physical and mental ability.

Q  I have been taking high doses of vitamins before getting pregnant. Can this affect my pregnancy?

High doses of vitamin A and D appear to cause an increased incidence of miscarriages and foetal abnormalities of the face, head, heart, retardation of behaviour and central nervous system. Care should be taken when taking vitamins and only those advised by your obstetrician. Accutane, a derivative of vitamin D often used in the treatment of acne can also cause abnormalities.

Q  I had  a chest xray and then discovered I was pregnant. will this harm my baby?

Xrays used for diagnosis are safe as the amount of radiation is extremely low. A chest xray delivers < 5 rads to you of which only a small amount will go to the baby. If a lead shield is used, the amount is negligible. Doses of >50 rads are required to possibly cause foetal malformations such as mental retardation, cataracts, small brain, blood cancer.

Q  Will a sauna or hotbaths affect my pregnancy?

High temperatures may cause foetal abnormalities. It is best to avoid both especially in the first 16 weeks of pregnancy when the central nervous system of the baby is developing. Exposure to high  temperatures has been shown to cause neural tube defects of the spine. The risk however is low. Neural tube defects can be diagnosed by an alpha foeto-protein blood test and a 2/3D scan of the foetal spine.

Q  Will contact with petrochemicals affect my pregnancy?

Breathing vapours or skin contact with certain chemical solvents such as polychlorinated biphenyls may cause abnormalities such as growth retardation and skin pigmentation.

Q  What medications can affect my pregnancy?

As a general rule you should avoid any medication in the first trimestor unless necessary. There are certain medications which are definitely harmful whentaken. The US Food and Drug Aministration in 1980 came out with the categorisation for use of drugs in pregnancy:
Category A: Adequately controlled studies on humans have shown no risk. Vitamins not exceeding the recommended daily allowance are under this category.
Category B: No evidence of risk in humans. Either animal studies show risk but human findings do not or if no adequate human studies have been done, animal studies are negative with regards to antihistamines, certain antibiotics with antifungals such as chlorpheniramine, penicillins, cephalosporins, sulphonamides, metronidazole, erythromycin, clindamycin, nystatin, prednisolone, insulin, vaccines such as hepatitis B, tetanus.
Category C: Risk cannot be ruled out as human studies are lacking. However, potentail benefits may justify the risk of use. This includes aspirin, betamethasone, codeine, dexamethasone, gentamycin, heparin, methyldopa, diazepam.
Category D: Positive evidence of risk to the foetus but potential benefits may outweigh the risks. This includes medroxyprogesterone, phenobarbitol, phenytoin, streptomycin, tetracycline, quinine.
Category X: Disallowed in pregnancy as studies have shown foetal risk outweighs all possible benefits. This includes clomiphene, oestrogen, ethanol, isotretinoin, live vaccines such as measles, mumps, smallpox and oral contraceptives.

Q  What antibiotics can I take and what cannot I take during pregnancy?

The majority of antibiotics are safe. Penicillins are widely prescribed and are safe during pregnancy. Tetracyclines can cause permanent staining of teeth, streptomycin, 8th nerve damage and hearing loss in 15% of infants.

Q  My GP has given me some cough mixture and anti-flu maedines. They they safe to take?

Cough mixtures should not be consumed for long periods. They are generally safe but if your cough is protracted ie more than 2 weeks, you should have yourself tested for mycoplasma chest infection or pneumonia rather than simply continuing with the cough mixture. High fever can be potentially harmful and should be contained below 38 degrees F.

Q  I am epileptic and suffer from frequent fits. I am on anticonvulsants. what effect do these drugs have on my pregnancy?

Specific patterns of abnormalities have been observed with different anti-convulsants. Dilantin can cause a syndrome characterised by abnormalities of the face, skull, limbs, heart and mental retardation. About 40% of exposed foetuss will have this abnormality. Tegretol also causes similar abnormalities. Trimethadone and paramethadone used in the treatment of minor convusions (petit mal convulsions) cause abnormalities in 85% exposed foetuss and should not be used.

Q  I have been taking sleeping tablets, valium. will this affect my pregnancy?

the reporst are conflicting but there are reported cases of foetal abnormalities, and evidence that valium does cross the placental barrier to the foetus. Certain major tranquilisers such as lithium have been proven to cause abnormalities.

Q  I was taking oral contraceptives when I discovered that I was pregnant. Will this affect my pregnancy?

Reported abnormalities include congenital heart defects, nervous system defects, limb and sex organ abnormalities. Sex organ abnormalities are usually seen with the higher dose oral contraceptives. the low dose contraceptives that are normally used today do not appear to have any effect on the foetus.

Q  I have been using the intrauterine contracetive device (IUCD) and discovered I am pregnant. What do I do?

You should go to see your obstetricians who will do certain tests to exclude an ectopic pregnancy. An IUCD increases the risk of ectopic pregnancies. An ultrasound scan will detremine if the pregnancy is healthy. If there is no bleeding and the pregnancy healthy, the IUCD can be removed and the baby delivered as normal. If there has been bleeding or the IUCD thread cannot be seen on vaginal examination, then the IUCD is left inside and can be removed during the delivery of the placenta. There are no consistent reports of adverse effects of the IUCD on the foetus. It is very safe to proceed wuth the pregnancy.

Q  I work with computers throughout the day. Will this harm my pregnancy?

Although there have been various reports of miscarriages with exposure to low electromagnetic waves, recent studies by the RCOG have shown that they do not increase the incidence of miscarriages or prematurity. and that it is safe to ahve prolonges exposure to computers.

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