Taking Drugs While Pregnant

What is a miscarriage?

It is the spontaneous loss of a pregnancy that occurs during the first 20 weeks of pregnancy, most commonly before 12 weeks. After 20 weeks the loss of the pregnancy is called a stillbirth. About 1 in 7 recognised pregnancies will miscarry and about 1 in 3 women will experience a miscarriage during their reproductive life. A miscarriage may occur so early in a pregnancy that a woman may have been unaware that she was pregnant. These miscarriages are often unreported. Sometimes a doctor or nurse may refer to a miscarriage as a “spontaneous abortion”. “Abortion” is the common medical term given to all pregnancies that end before 20 weeks (both miscarriages and terminations). Miscarriage can be a difficult and traumatic experience for some women. For others, it may happen so early that the pregnancy was undetected.

Why does miscarriage occur?

It is generally unknown what causes miscarriages. Basically, miscarriage occurs because the foetus did not develop properly, probably because of a chromosomal or other genetic abnormality. The pregnancy is not normal and miscarriage is nature’s way of taking care of the problem.

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Thomaz Rafael Gollop and Ivan Salzo

Abstract

Fetal hydantoin syndrome (FHS) is a set of disruptions occasionally present in fetuses exposed in utero to phenytoin or other anticonvulsants. Administration of phenytoin in early pregnancy may impair proper psychomotor performance expected for children’s development. Several combined phenotypic markers delineate the syndrome, but the presence of single clinical signs is more common. There is controversy about the etiology of FHS. Associated disruptions may be related to a deficiency in a detoxifying enzyme (epoxide hydrolase), vascular problems, and/or factors not yet known. Genetic causes are believed to influence susceptibility to the drug. This text reports an unusual pattern of malformations detected in an ultrasound scan (gastroschisis, sacral meningomyelocele, and absence of the right lower limb) and in the anatomopathological study (left-side gastroschisis, sacral meningomyelocele, scoliosis, left clubfoot, absence of the right lower limb, and pectus carinatum) of a fetus whose mother took phenytoin. These defects may have been provoked by exposure to the drug during embryogenesis. In view of similar malformations observed in cases of prenatal exposure to cocaine, a recognized vasoconstrictor, it is suggested that vascular disruptions of hemodynamic origin constituted the event leading to some of the anomalies caused in the developing embryo. A complication of the chorionic villus sampling procedure, used for cytogenetic analysis, is another possibility.

Introduction

Phenytoin (Dilantin), the new denomination for diphenylhydantoin, is an efficient hydantoin anticonvulsant. Phenytoin is presumed to disrupt normal development of some fetuses when administered during pregnancy. In the 60’s, effects attributed to this medication were grouped into a somewhat recognizable pattern of anomalies (Briggs et al., 1994): fetal hydantoin syndrome (FHS). Classical indicators of FHS were classified by Hanson (1986) into three distinct sets:

1) abnormalities of pre- and post-natal growth – this set includes microcephaly;

2) delay in development, and impaired psycho-motor performance – cases of mental retardation are common;

3) dysmorphic craniofacial features and limb anomalies.

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