Dwight P. Cruikshank

Effects of magnesium sulfate treatment on perinatal calcium metabolism

To evaluate the effects of maternal magnesium sulfate treatment on neonatal magnesium and calcium homeostasis, the authors studied 23 term neonates whose mothers had received intravenous magnesium sulfate for preeclampsia and compared them with 14 control neonates. Total and ionized calcium, magnesium, phosphorus, and albumin were measured in maternal and umbilical blood; total calcium, magnesium, phosphorus, and albumin were measured serially in the newborn infants. Magnesium levels were higher in treated than in control infants in umbilical venous and arterial blood samples and in the neonatal blood samples 2, 12, and 24 hours after delivery. However, at 48 hours and beyond there was no difference in serum magnesium levels between treated infants and controls. Calcium levels were not significantly different in treated versus control subjects in umbilical blood or in any neonatal samples. There was no correlation between the maternal magnesium concentration at delivery and the levels of calcium in umbilical or neonatal blood. These data indicate that maternal magnesium sulfate therapy does not cause neonatal hypocalcemia and that the induced neonatal liypermagnesemia is resolved within the first 48 hours of life.

Fetal platelet counts in the obstetric management of immunologic thrombocytopenic purpura

The optimal method of infant delivery for gravida women with immunologic thrombocytopenic purpura (ITP) is controversial because of the unpredictability of the fetus developing thrombocytopenia and the uncertainty of the relation between vaginal birth and intracranial hemorrhage in thrombocytopenic infants. We have employed the technique of platelet counts on fetal scalp blood obtained prior to or early in the course of labor in 12 patients with ITP. A count of 50,000/cu mm, selected on the basis of literature review and retrospective analysis of our own experience, was used to define fetal thrombocytopenia. Three thrombocytopenic fetuses were delivered by cesarean section. Trial labor was permitted in the other nine cases in which fetal scalp platelet count exceeded 50,000/cu mm. The outcome was good in all instances. If cesarean section is to be employed in ITP patients to obviate the potential danger of fetal hemorrhage with vaginal delivery, the use of platelet counts of fetal scalp blood seems to provide the most rational basis for management at present.

Antiplatelet antibodies and platelet counts in pregnancies complicated by autoimmune thrombocytopenic purpura

In 48 pregnant women with autoimmune thrombocytopenic purpura, no consistent correlation was found between the infant platelet count and either the maternal platelet count, a previous maternal splenectomy, or maternal treatment with corticosteroids. Although the concentration of antiplatelet antibody in maternal serum frequently reflected the severity of neonatal thrombocytopenia, a number of exceptions to this observation limited the clinical usefulness of the test for individual patients. Antiplatelet antibody levels in the amniotic fluid were always low. A twin gestation in this series of patients in which one infant was thrombocytopenic and the other was not also showed that no antepartum maternal clinical characteristic or laboratory test can accurately predict the fetal platelet count. Only fetal platelet counts from scalp samples obtained prior to or early in labor from 25 patients with autoimmune thrombocytopenic purpura proved to be reliable in assessing the degree of fetal thrombocytopenia and selecting the appropriate route of delivery.

Should all women be offered elective cesarean delivery

In this issue, Dietz and Bennett report that vaginal delivery, especially operative vaginal delivery, was associated with increased mobility of the urethra, bladder, and rectum at 2 to 3 months postpartum. Bladder neck descent differed significantly between women with prelabor cesarean delivery and those with spontaneous vaginal delivery, whereas no significant difference was found between those with cesarean deliveries done during labor and those with vaginal delivery. These findings raise again the issue of whether there is a role in modern obstetrics for elective cesarean delivery before labor for prevention of pelvic floor disorders. Various pathophysiologic studies have demonstrated marked changes after vaginal delivery to levator muscles, nerves, and, as shown in this issue, pelvic support. It is clear that parous women are more likely to have pelvic organ prolapse, fecal incontinence, and urinary incontinence than women who have not borne children. There is ample epidemiological evidence that vaginal delivery appears to be the strongest risk factor for pelvic floor disorders, at least in young and middle-aged women. In women participating in the Women’s Health Initiative, those who had borne at least one child were twice as likely to have uterine prolapse, rectocele, and cystocele as nulliparas, after adjusting for age, ethnicity, body mass index, and other factors. Fecal incontinence after anal sphincter disruption at the time of vaginal delivery is a particularly devastating disorder related to this mode of delivery. Dietz and Bennett’s article follows quickly on Rortveit and colleagues’ large population-based study in which women who delivered vaginally had a 2.2-fold higher risk of moderate or severe urinary incontinence than those who delivered solely by cesarean. Those authors concluded that a woman’s risk of moderate or severe incontinence would be decreased from about 10% to about 5% if all of her children were delivered via cesarean. This is consistent with the bulk of the literature on the epidemiology of moderate to severe urinary incontinence in younger and middle-aged women. Although the decreased risk of moderate and severe urinary incontinence after cesarean delivery is the focus of Rortveit’s study, two additional findings warrant equal attention, as they help to put the debate of the role of “prophylactic” cesarean deliveries into perspective. First, somewomenwho delivered solely via cesarean also had moderate or severe incontinence. Similarly, in Dietz and Bennett’s study some women who delivered via cesarean before the onset of labor had bladder neck descensus postpartum. Secondly, in Rortveit’s population the protective effect of cesarean delivery on urinary incontinence dissipated by age 50 such that older women had the same rate of urinary incontinence regardless of their delivery mode. Although it is tempting to attribute all pelvic floor disorders to childbirth practices, the truth is more complex and just beginning to be sorted out. Dietz and Bennett report differences between third-trimester and postpartum mobility measurements. The prenatal status of pelvic organ support was not described, and thus the reader cannot know whether the support defects found in some pregnant women were present already or occurred because of the pregnancy. However, others have also found increased pelvic organ prolapse and increased urinary incontinence in Ingrid Nygaard, MD

Midtrimester amniocentesis. An analysis of 923 cases with neonatal follow-up

Maternal, fetal, and neonatal results and complications were analyzed after 923 genetic amniocenteses. Maternal age of 35 years and beyond was associated with a 2.0% risk of fetal trisomy 21 and a 3.0% risk of all major chromosome abnormalities. Comparable rates for women aged 40 and beyond were 4.8% and 7.2%. Neural tube defects were detected in 0.15% of procedures done for maternal age and 3.4% of those done for a previous involved child. The risk of spontaneous abortion as a result of amniocentesis was 0.2% to 1.4%. Mahogany or green fluid was associated with a 29% rate of fetal loss. Unexplained midtrimester elevations of maternal serum alpha-fetoprotein were associated with a 38% risk of a subsequent low-birth weight infant. The only neonatal complication associated with amniocentesis was an apparent marked increase in the incidence of lower-extremity orthopedic abnormalities.

Calcium metabolism in diabetic mother, fetus, and newborn infant

Peripheral blood levels of the minerals and hormones involved in calcium homeostasis were measured in insulin-dependent diabetic patients at delivery, and in umbilical arterial and venous blood. The minerals were also measured in neonatal blood at 24 hours of age. Insulin-dependent diabetic patients at delivery have depressed serum levels of parathyroid hormone, although serum total and ionized calcium levels are not different from those of nondiabetic patients. Fetuses of diabetic mothers are hypocalcemic and have reduced parathyroid hormone levels. Infants of diabetic mothers demonstrate early neonatal hypocalcemia. No differences between diabetic and control patients could be demonstrated in terms of calcitonin or phosphorus levels, in either mother, fetus, or neonate.

Obstetric malpresentations: Twenty years' experience

Abstract Two hundred fifty-eight cases of face, brow, compound, and shoulder presentation are analyzed with regard to incidence, etiology, management, and outcome. Maternal parity is etiologically significant in face and shoulder presentation, while prematurity is significant only in compound and shoulder presentation. Cephalopelvic disproportion accompanies face, brow, and shoulder presentation. All four malpresentations are associated with an increased incidence of premature rupture of the membranes. X-ray pelvimetry is most useful in the management of brow presentation. Vaginal delivery can be expected in 88 per cent of face presentations and 70 per cent of brow presentations. In the management of shoulder presentation, version and extraction should be reserved for very immature infants and classical cesarean section should be employed very infrequently.

Breast milk magnesium and calcium concentrations following magnesium sulfate treatment

Abstract Intrapartum magnesium sulfate treatment increases breast milk/colostrum magnesium levels significantly for only 24 hours after discontinuation of the infusion. After 24 hours, milk magnesium levels are the same as those of control subjects. The breast-fed infant of a treated mother would receive only 1.5 mg of magnesium more than the infant of a nontreated mother. Breast milk/colostrum calcium levels are not affected by magnesium sulfate therapy.

A Prospective Evaluation of X-ray Pelvimetry

One hundred four consecutive patients undergoing x-ray pelvimetry were analyzed prospectively in an attempt to evaluate the efficacy of this procedure. Comparison was made between prepelvimetry and post-pelvimetry clinical management plans. Roentgenographic pelvic measurements led to prompt and significant alterations in clinical management plans in only one of 67 patients with vertex presentation and one of 37 with breech presentation. In 98% of patients, no change in immediate clinical management plan was made on the basis of x-ray pelvimetry findings.