Magnesium tocolysis and neonatal bone abnormalities: a controlled study
Article Abstract:
Magnesium sulfate is commonly used as a tocolytic agent to prevent premature labor. To learn whether this drug has adverse effects on the bones of newborns, 11 neonates were assessed. The infants were the products of seven pregnancies, one of which involved triplets; four, twins; and two, singletons. Their mothers had received intravenous (IV) magnesium sulfate for more than seven days during the course of pregnancy. Two unexposed infants were matched with each subject and studied as controls; the infants were matched for gestational age and number (that is, twins were matched with twins). After the infants underwent chest X-rays, and the appearance of the proximal humerus (the part of the upper arm bone visible on a chest X-ray) was evaluated. The bones were classified as showing a definite abnormality, a probable abnormality, a possible borderline abnormality, or as normal. Results showed that 6 of the 33 X-rays were classified as definitely abnormal; none as probably abnormal; 4 as possibly borderline; and 23 as normal. None of the 22 unexposed newborns had an X-ray with a definitely or probably abnormal humerus; all 6 of the definitely abnormal bones were those of exposed infants. The abnormalities are described. In cases of multiple births, the results of the siblings were the same, that is, both abnormal or both normal. Four of the seven pregnancies treated with magnesium sulfate showed abnormalities of the proximal humerus. A brief review of the literature describes bone abnormalities in infants born to mothers who received prolonged IV magnesium treatments. In the current study, the mothers who had been exposed to these treatments had also been treated with other drugs known to affect the fetal skeleton in animal studies. The clinical significance of these findings is not clear, but it seems that these abnormalities disappear early in life. (Consumer Summary produced by Reliance Medical Information, Inc.)
Publication Name: Obstetrics and Gynecology
Subject: Health
ISSN: 0029-7844
Year: 1991
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The role of hCG in regulation of the thyroid gland in the normal and abnormal pregnancy
Article Abstract:
Human chorionic gonadotropin (hCG) is a substance produced by the chorionic villi, the portion of the placenta that contains blood vessels and projects into the wall of the uterus. The placenta is the tissue that provides nourishment to the fetus. The detection of hCG serves as a marker for pregnancy. The structure of hCG is very similar to that of the pituitary hormone, thyroid-stimulating hormone (TSH), which stimulates the thyroid gland to release thyroid hormones. Thus, hCG may also stimulate the thyroid gland. The incidence of hyperthyroidism, or elevated activity of the thyroid gland, is increased in patients with trophoblastic tumor, a malignancy of the fetal tissues that secretes large amounts of hCG. In addition, thyroid function appears to change during normal pregnancy, which is indicated by changes in thyroid tests. Although hCG can attach to thyroid membranes from different species, it does not consistently activate the enzyme adenylate cyclase, which is involved in thyroid gland function. Although hCG has been shown to stimulate the thyroid gland, its effects on human thyroid cells are inconsistent. Elevated levels of hCG in early pregnancy are associated with an increase in levels of thyroid hormone and reduced levels of TSH, which is consistent with enhanced thyroid gland activity. A specific rat thyroid cell line, or type, referred to as FRTL-5, was stimulated by some substance in pregnant blood that has similar activity to that of hCG. This hCG-like activity in pregnant blood may be responsible for changes in thyroid function during pregnancy. The current data suggest that hCG has some ability to stimulate the thyroid gland. Hence, the activity of the thyroid gland during pregnancy may be controlled by two factors, hCG and TSH (Consumer Summary produced by Reliance Medical Information, Inc.)
Publication Name: Obstetrics and Gynecology
Subject: Health
ISSN: 0029-7844
Year: 1991
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