Intra-uterine treatment of a hypothyroid fetus.

A woman in her 24th week of gestation was referred for treatment of hypothyroidism, after she underwent radioablation of the thyroid during the 13th week of gestation. Because of the high risk of hypothyroidism in the fetus, prenatal administration of intramuscular T-4 to the fetus was begun at 32 weeks. The last dose of T-4 was given 2 weeks before delivery; cord blood levels of T-4 and T-3 were undetectable and the TSH concentration was markedly elevated. The case illustrates several important physiological concepts regarding thyroid hormone and TSH metabolism in the fetal-placental unit, including the minimal placental permeability to iodothyronines and TSH, independent function (including feedback control) of the fetal hypothalamic-pituitary-thyroid axis, and the TSH response at parturition. In addition we suggest that administration of T-4 to the hypothyroid fetus in utero is an acceptable modality of treatment and may help to minimize irreversible mental retardation in known high risk infants. However, further studies are necessary to assess the effectiveness and safety of this approach.

Aerobic and anaerobic bacterial flora of the maternal cervix and newborn gastric fluid and conjunctiva: a prospective study.

Aerobic and anaerobic cultures were performed on cervical swabs from 35 mothers and their newborn infants' gastric aspirates and conjunctival sacs. Four hundred seventy-nine isolates were obtained; 287 were aerobes and 192 were anaerobes. The cervical and gastric cultures overall yielded a similar flora, but this was not always the case when one compared mothers with their own newborn infants. The conjunctival cultures yielded about half of the number of bacteria per specimen that the gastric contents yielded, and a repeat conjunctival culture done 48 hours later showed a marked reduction in the number of potentially pathogenic bacteria isolated. The predominant aerobes isolated were Staphylococcus epidermidis, diphtheroids, viridans streptococci and Haemophilus vaginalis. The predominant anaerobes were the Bacteroides fragilis group, Propionibacterium acnes, Peptococcus, other Bacteroides and Peptostreptococcus organisms. Statistical analysis revealed significant positive correlation between the isolation of certain groups of organisms and increased duration of pregnancy, increased baby's weight, and prolonged duration of labor.

Effect of meconium contamination on amniotic fluid lecithin: sphingomyelin ratio.

Studies on the lecithin: sphingomyelin (L:S) ratio in amniotic fluid were made before and after the addition of meconium in 130 normal pregnancies. The meconium was collected from premature and term infants after delivery. That which was collected from premature neonates had no significant effect on the mean L:S ratio of amniotic fluid; in 28% (17 of 60), however, the L:S ratio was elevated by 0.1 to 0.2, though in none by more than 0.2. When meconium collected from term neonates was added to amniotic fluid, it significantly increased the mean L:S ratio of amniotic fluid when the baseline L:S ratio was between 1.0 and 1.9 (P less than .01); in 56% (39 of 70), the L:S ratios were elevated by 0.1 to 0.5, though none increased by more than 0.5. This study suggests that when amniotic fluid is contaminated with meconium, an L:S ratio of 2.2 in premature pregnancies and 2.5 or greater in term pregnancies retains its original predictive value.

Lecithin:sphingomyelin ratio in pregnancies complicated by insulin-dependent diabetes mellitus.

One hundred forty-one samples of amniotic fluid in 105 pregnancies from 95 insulin-dependent diabetics were analyzed for the lecithin:sphingomyelin (L:S) ratio. Fetal pulmonary maturity seemed to progress at a normal rate. The mean L:S ratio was not significantly different in diabetic and nondiabetic patients at various stages of gestation. Only 3 cases of respiratory distress syndrome (RDS) were observed in 77 infants with an L:S ratio of 2.0 or more delivered of diabetic mothers within 72 hours of amniocentesis. This 3.9% incidence of RDS in infants of diabetic mothers with L:S ratios of more than 2.0 was not significantly higher than the 1.5% incidence in the nondiabetic mothers. It is concluded that by using the method of Gluck, an L:S ratio of 2.0 or greater at 36 weeks' gestation or later is a reliable indicator of fetal lung maturity in insulin-dependent diabetic pregnancies, and abdominal delivery after 36 weeks' gestation does not increase the risk of RDS in a diabetic pregnancy with an L:S ratio at 2.0 or more.

Fetal and neonatal cardiopulmonary response to histamine.

Effects of intravenous histamine and its H1 receptor blocker (Benadryl) were investigated in near-term fetal and in newborn lambs. Fetuses were studied before and after closure of the ductus arteriosus. Newborn lambs were chronically instrumented and the same animal was tested periodically from 3 to 70 days old. The results show that a) in the fetus whose pulmonary vascular resistance is already high, histamine produces a profound pulmonary vasodilation; b) in contrast, in the neonate with reduced pulmonary vascular resistance, histamine produces pulmonary vasoconstriction similar to that of the adult; c) both responses can be attenuated by Benadryl indicating that they are mediated by the same receptor; d) in the fetus, histamine produces marked constriction of the ductus arteriosus which could be partly attributed to the pulmonary vasocilatation; and e) when neonatal pulmonary vascular resistance was raised by hypoxia, histamine elicited a biphasic response, part of which was blocked by Benadryl. These findings are discussed in terms of their possible role in cardiovascular and pulmonary changes that occur after birth.

Continuous Fetal Scalp and Carotid Artery Oxygen Tension Monitoring in the Sheep.

Fetal scalp and carotid PO2 were recorded continuously by polargraphic oxygen electrodes at several levels of maternal oxygenation. The results were compared to measurements obtained by intermittent blood samples using the radiometer blood gas analyzer. There was a good correlation between the PO2 values measured by the implanted oxygen electrodes and by conventional analyses of blood samples collected anaerobically. Electrode measurements differed from the control radiometer values by a mean of +/- 1.2 mmHg; 2 SD= +/- 2.50. Scalp PO2 recordings were lower but paralleled the carotid recordings under varying degrees of maternally inspired O2 concentrations. Thus scalp PO2 levels reflect closely those in the central fetal circulation. Administration of 95% O2 to the mother resulted in a 27% increase of scalp PO2 and a 29% increase in the carotid artery PO2 when compare to room air.

Maternal and fetal hemodynamic effects of diazoxide.

Effects of diazoxide on systemic and uterine hemodynamics as well as on fetal circulation and blood respiratory gases were investigated in chronically instrumented pregnant sheep. Diazoxide was administered intravenously either to the ewe or directly to the fetus in doses calculated on the basis of body weight. Transfer of drug across placenta was also investigated. Results showed that: a) when injected into the mother, there was consistent hypotensive effect with increased cardiac output and decreased systemic vascular resistance; uterine blood flow might not change or might decrease slightly with moderate hypotension; when maternal systemic arterial pressure fell to critical closing pressure level, uterine flow decreased significantly; but despite these maternal changes, the fetal circulatory functions were not significantly altered; b) when injected into the fetus in doses up to 15 mg/kg, diazoxide failed to alter fetal circulation appreciably; c) diazoxide crossed the placenta when injected intoeither mother or fetus according to a definite gradient; fetal levels were always lower than maternal levels because of rapid loss of the drug by the fetus; d) moderate maternal and fetal hyperglycemia occurred after drug administration.

Midazolam and diazepam: maternal and fetal effects in the pregnant ewe.

Maternal and fetal hemodynamic effects and placental transfer of midazolam (RO 21-3981, Hoffman-LaRoche) and diazepam were studied in chronically instrumented pregnant ewes. Diazepam administration resulted in greater increases of maternal and fetal heart rates and maternal blood pressure, and greater alteration of total uterine blood flow than did administration of comparable doses of midazolam. Neither drug altered fetal mean arterial pressure or maternal and fetal respiratory gases. Although the absolute blood concentrations were higher, the fetal:maternal drug concentration ratios were consistently less for midazolam than for diazepam, suggesting less placental permeability of midazolam.

The jejunoileal bypass and pregnancy.

The combined experience regarding pregnancy in the jejunoileal bypass patient is too limited to draw any firm conclusions. Nevertheless, the observations made in this report suggest that: (1) Safe elapse of time from shunt procedure to pregnancy has not been established and the risk of pregnancy during the period of rapid postoperative weight loss remains speculative. Limited experience suggests that there is only a relative risk during this period of metabolic derangement. (2) Pregnancy does not appear to influence the expected clinical or metabolic changes commonly observed postoperatively in the bypass patient. Dietary supplementation should be based on the weight trend, serial laboratory chemistries, and the presence or absence of ketones in the urine. (3) Neonatal outcome appears to be good in pregnancies of patients with intestinal shunt operations. It has been suggested that small for dates babies are frequent in this group of patients. This point lacks conclusive documentation. (4) Birth control pills for contraception are not advised in intestinal bypass patients because of the uncertain intestinal absorption of the medication and the subsequent risk of an unwanted pregnancy.

Antihypertensive drugs in pregnancy.

This article considers the pathophysiology, diagnosis, and etiologies of hypertensive conditions, and considers specific agents for treating this condition. It also reviews the side effects of these agents and their efficacy, and details their use in the hypertensive pregnant patient.

The treatment of gestational hypertension.

The development of a logical and physiologically sound approach to the management of gestational hypertension presents a formidable challenge to both obstetrician and internist. The maternal and fetal risks and sequelae are well known and significant. Therefore, understanding the pathophysiology of the particular hypertensive syndrome or disease being treated is of great importance if a rational approach to treatment is to be accomplished. In this discussion we will present the pharmacology of the various antihypertensive agents currently being used, followed by a brief discussion of our current concept of the pathophysiology of the three major types of hypertension seen during pregnancy and finally by our suggested management.

Experimental renal hypertension in pregnant sheep. II. Response to a one-kidney model.

Pelvic blood flow was serially determined in 19 pregnant ewes before and after the induction of one-kidney renal hypertension. The six twin gestations and 13 singleton gestations behaved similarly for all parameters, except renal blood flow. After the renal preparatory surgical procedure, there was a 19% increase in mean arterial pressure and an 18% increase in pelvic blood flow, with pelvic vascular resistance being unchanged. After right renal artery constriction, there was a 14% further increase in mean arterial pressure, whereas pelvic blood flow increased only 3.5% and pelvic vascular resistance increased nearly 9%. Thereafter, although the arterial pressure remained elevated, the pelvic blood flow decreased and pelvic vascular resistance increased. Statistical analysis by means of a general linear model and covariance before and after renal artery constriction revealed significant changes in arterial pressures, pelvic blood flow, and pelvic vascular resistance.