Effect of prenatal zidovudine on disease progression in perinatally HIV-1-infected infants

OBJECTIVE

To determine the influence of prenatal zidovudine (ZDV) prophylaxis on the course of HIV- 1 infection in children by comparing the clinical outcome of infants born to HIV- 1-seropositive mothers who did versus those who did not receive ZDV during pregnancy.

METHODS

Medical records of HIV-1-seropositive mothers and their infants were reviewed retrospectively. Participants were divided according to maternal ZDV use: no ZDV (n = 152); ZDV (n = 139). The main outcome measure was rapid disease progression (RPD) in the infant, defined as occurrence of a category C disease or AIDS-related death before 18 months of age.

RESULTS

HIV vertical transmission rates were significantly different (no ZDV versus ZDV: 22.3% versus 12.2%; p = .034). Among infected infants, the RPD rate was 29.4% in the no ZDV group compared with 70.6% in the ZDV group (p = .012), and prematurity was significantly associated with a higher risk of RPD (p = .027).

CONCLUSIONS

The rate of RPD was significantly higher among perinatally infected infants born to HIV-infected mothers treated with ZDV than among infected infants born to untreated mothers. The decreased proportion of infected infants with nonrapid disease progression in the former group might be related to the ability of ZDV to block intrapartum transmission preferentially and also to nonrapid disease progression resulting from intrapartum transmission.

Strategic learning in healthcare organizations

There is no definitive blueprint for the healthcare organization involved in strategic learning. However, what distinguishes strategic learning institutions is their acknowledgment that they must discover their own paths and solutions rather than blindly follow a detailed strategic mandate from administration. Answers to their most critical implementation and adaptive questions will not flow down ready-made from above, but will be tailored to meet the requirements of their own particular situation. Strategic learning organizations have certain attributes in common in developing their own answers: They continuously experiment rather than seek final solutions. They favor improvisation over forecasts. They formulate new actions rather than defend past ones. They nurture change rather than permanence. They encourage creative conflict rather than tranquillity. They encourage questioning rather than compliance. They expose contradictions rather than hide them (Weick 1977). Most importantly, strategic learning organizations realize that successful strategic change is best undertaken as a process of learning (O'Sullivan 1999). Healthcare organizations can no longer afford the illusion of traditional strategic planning, with its emphasis on bureaucratic controls from the top to the bottom. They must embrace the fundamental truth that most change occurs through processes of learning that occur in many locations simultaneously throughout the organization. The initial step in discovering ways to improve the capability of healthcare organizations is to adapt continuously while fulfilling their mission. Healthcare leaders must create a shared vision of where an institution is heading rather than what the final destination will be, nurture a spirit of experimentation and discovery rather than close supervision and unbending control, and recognize that plans have to be continuously changed and adjusted. To learn means to face the unknown: to recognize that we do not possess all the answers; to concede that we do not always know what to do; to admit that past actions and solutions may no longer be appropriate, in fact may have been the incubators of today's problems; to question basic assumptions long held about running the institution; and to make ourselves vulnerable to the political dynamics prevalent in all organizations. Hospitals and other healthcare organizations must seek to develop and maintain a continuing state of readiness in which everyone in the organization, from front-line clinician to senior management, is poised to act in anticipation of and in response to unforeseen changes in the environment and to learn from their own experiences in confronting the future.

Influence of human immunodeficiency virus infection on pelvic inflammatory disease

OBJECTIVE

To examine the influence of human immunodeficiency virus (HIV) infection on clinical and microbiologic characteristics of pelvic inflammatory disease (PID).

METHODS

Forty-four HIV-infected women and 163 HIV noninfected women diagnosed with PID by standard case definition were evaluated by using clinical severity scores, transabdominal sonograms, and endometrial biopsies. After testing for bacterial infections, patients were prescribed antibiotics as recommended by the Centers for Disease Control and Prevention (CDC).

RESULTS

Symptoms of PID and analgesic use before enrollment did not differ by HIV serostatus. More HIV-infected women had received antibiotics before enrollment (40.9% versus 27.2%, P =.08), a factor associated with milder signs regardless of serostatus. More HIV-infected women had sonographically diagnosed adnexal masses at enrollment (45.8% versus 27.1%, P =.08), a difference that yielded higher median severity scores (17.5 of 42 points versus 15 of 42 points, P =.07). However, those differences were not significant at the P <.05 level. Mycoplasma (50% versus 22%, P <.05) and streptococcus species (34% versus 17%, P <.05) were isolated more commonly from biopsies of HIV-infected women. Within 30 days after enrollment, HIV-infected women generally responded as well to therapy as HIV-noninfected women did, regardless of initial CD4 T-lymphocyte percentage.

CONCLUSION

Among women with acute PID, HIV infection was associated with more sonographically diagnosed adnexal masses. Clinical response to CDC-recommended antibiotics did not differ appreciably by serostatus. Mycoplasmas and streptococci were isolated more commonly from HIV-infected women, but those organisms also might be associated with PID in immunocompetent women.

Perinatal outcome of twin pregnancies with one structurally affected fetus: a case-control study

OBJECTIVE

To determine whether one structurally affected fetus of a twin pregnancy further increases the risk of preterm delivery and to compare perinatal morbidity and mortality in these pregnancies with twin gestations with structurally normal fetuses.

STUDY DESIGN

The cases (n = 25) included all twin gestations diagnosed from 1991 to 1994 with a sonographically detected fetal anomaly and a structurally normal co-twin delivered after 24 completed weeks' gestation. The control group consisted of 547 twin gestations delivered during the study period with no sonographically detected structural anomalies in either twin.

RESULTS

Compared with controls, pregnancies with a single anomalous fetus (cases) delivered at a significantly lower gestational age (mean +/- SD: 34.0 +/- 3.2 weeks versus 35.6 +/- 3.2 weeks; p = 0.019) and had a significantly increased preterm delivery rate (76.0% vs 55.4%; p = 0.042). There was no significant difference in the incidence of intraventricular hemorrhage or respiratory distress syndrome, yet the perinatal mortality (80.0/1000 vs 6.4/1000; p = 0.000) and the average nursery stay (45.5 +/- 43.3 days versus 17.0 +/- 24.0 days; p = 0.003) were significantly increased for cases compared with controls. In addition, a significantly greater birth weight discordancy (> or = 30%) was seen in cases compared with controls (32.0% versus 9.1%; p = 0.002). The normal co-twin did not show any significant difference in the perinatal outcome variables studied when compared with controls.

CONCLUSION

Compared with structurally normal twin pairs, twin gestations with a single anomalous fetus are at a significantly increased risk for preterm delivery. In addition, the anomalous fetus, but not the structurally normal co-twin, has a significantly increased mortality rate and a longer nursery stay. Finally, despite the increased risk for preterm delivery in twin pregnancies with one anomalous fetus, it is the nature of the anomaly itself that dictates the perinatal outcome.

Risk factors and opportunities for prevention of early-onset neonatal sepsis: a multicenter case-control study

BACKGROUND

Early-onset group B streptococcal (GBS) prevention efforts are based on targeted use of intrapartum antibiotic prophylaxis (IAP); applicability of these prevention efforts to infections caused by other organisms is not clear.

METHODS

Multicenter surveillance during 1995 to 1996 for culture-confirmed, early-onset sepsis in an aggregate of 52 406 births; matched case-control study of risk factors for GBS and other sepsis.

RESULTS

Early-onset disease occurred in 188 infants (3.5 cases per 1000 live births). GBS (1.4 cases per 1000 births) and Escherichia coli (0.6 cases per 1000 births) caused most infections. GBS sepsis less often occurred in preterm deliveries compared with other sepsis. Compared with gestation-matched controls without documented sepsis, GBS disease was associated with intrapartum fever (matched OR, 4.1; CI, 1.2-13.4) and frequent vaginal exams (matched OR, 2.9; CI, 1.1-8. 0). An obstetric risk factor-preterm delivery, intrapartum fever, or membrane rupture >/=18 hours-was found in 49% of GBS cases and 79% of other sepsis. IAP had an adjusted efficacy of 68.2% against any early-onset sepsis. Ampicillin resistance was evident in 69% of E coli infections. No deaths occurred among susceptible E coli infections, whereas 41% of ampicillin-resistant E coli infections were fatal. Ninety-one percent of infants who developed ampicillin-resistant E coli infections were preterm, and 59% of these infants were born to mothers who had received IAP.

CONCLUSIONS

Either prenatal GBS screening or a risk-based strategy could potentially prevent a substantial portion of GBS cases. Sepsis caused by other organisms is more often a disease of prematurity. IAP seemed efficacious against early-onset sepsis. However, the severity of ampicillin-resistant E coli sepsis and its occurrence after maternal antibiotics suggest caution regarding use of ampicillin instead of penicillin for GBS prophylaxis.

Pharmacokinetics of didanosine in antepartum and postpartum human immunodeficiency virus--infected pregnant women and their neonates: an AIDS clinical trials group study

Didanosine (ddI) pharmacokinetics in antepartum and postpartum human immunodeficiency virus (HIV)-infected women and their neonates were studied. HIV-infected pregnant women received an intravenous (iv) ddI infusion (1.6 mg/kg/h) or an oral dose (200 mg bid or 125 mg bid) at 31 weeks antepartum and 6 weeks postpartum. Blood samples were obtained regularly up to 6 or 8 h after drug administration. The same oral dose of ddI (bid) was administered until labor began. Then, ddI was infused iv until delivery. An oral pharmacokinetic study (60 mg/m2) was conducted in infants at day 1 and at week 6 after birth. Plasma concentrations of ddI were measured by radioimmunoassay. After iv ddI administration, only the maternal plasma clearance was found to be significantly increased antepartum (1028+/-231 mL/min) versus postpartum (707+/-213 mL/min). No pharmacokinetic parameters after oral administration were significantly affected by pregnancy. The pharmacokinetics of ddI in the neonates were highly variable. We conclude that the oral ddI dose need not be adjusted during pregnancy.

Singleton term breech deliveries in nulliparous and multiparous women: a 5-year experience at the University of Miami/Jackson Memorial Hospital

OBJECTIVE

The purpose of this retrospective study was to evaluate the feasibility of planned vaginal delivery, the maternal morbidity and mortality, and the short-term perinatal outcome in selected multiethnic women at term with singleton breech presentations.

STUDY DESIGN

Singleton breech deliveries were identified from the delivery database between January 1, 1989, and December 31, 1993. A retrospective chart review identified 310 nulliparous and 711 multiparous women at term (37-42 weeks) for a total of 1021. Parameters studied included the success rate of planned vaginal deliveries and the incidences of maternal morbidity, perinatal morbidity, and mortality as a whole stratified by parity and mode of delivery. The Student t test, chi(2) test, and Fisher exact test were used for statistical analysis.

RESULTS

Among 1021 women with singleton fetuses in a breech position at term, 191 were candidates for vaginal delivery, and 135 (70.7%) of these deliveries were successful. By parity, 12.3% of 310 nulliparous women and 21.5% of 711 multiparous women were candidates for vaginal delivery; 50% of the former and 75.8% of the latter underwent vaginal delivery. Maternal morbidity was more commonly associated with multiparity and cesarean delivery. Newborn intensive care admissions were equally distributed by parity, and significantly more were for vaginal than cesarean deliveries (17.4% vs 10.8%, P =.036). Premature rupture of the membranes complicated deliveries in 23.9% of the nulliparous women and only 6.5% of the multiparous women (P =.000).

CONCLUSION

In this multiethnic population 70.7% of candidates selected for attempted vaginal breech delivery at term were successful. The remaining 29.3% underwent cesarean delivery for labor disorders or nonreassuring fetal heart rate patterns.

History of gestational diabetes, insulin resistance and coronary risk

The purpose of this study was to examine characteristics associated with the insulin metabolic syndrome, including insulin resistance, abnormal glucose tolerance, dyslipidemia, obesity, and elevated blood pressure, among women who have experienced gestational diabetes. 39 nondiabetic, young (20-42 years), postpartum (3-18 months) white women were recruited from obstetrical clinics. Twenty-one women had a history of gestational diabetes; 18 had uncomplicated pregnancies. Multivariate analyses revealed a significant difference between groups in insulin resistance (M, measured by euglycemic clamp) and insulin levels (from an oral glucose tolerance test), with insulin resistance showing a statistically stronger difference than insulin levels. Groups also differed significantly when compared on a set of variables associated with insulin metabolic syndrome: glucose tolerance, triglycerides, blood pressure, and body-mass index. Using insulin resistance as a covariate eliminated these group differences, suggesting that insulin resistance is the key factor underlying insulin metabolic syndrome. The higher risk of later developing type 2 diabetes and hypertension in women who have a history of gestational diabetes is explicable by their poorer profile on variables associated with insulin metabolic syndrome, and appears to be attributable to insulin resistance. Thus, insulin resistance appears to distinguish young women at risk for cardiovascular disease.

A double-blind randomized trial of two dose regimens of misoprostol for cervical ripening and labor induction

OBJECTIVES

The objective of this study was to compare the efficacy and safety of two dosing regimens of misoprostol for cervical ripening and labor induction.

METHODS

Patients who fulfilled the study criteria were randomized to received misoprostol 25 microg or 50 microg intravaginally every 3 h for a total of eight doses for cervical ripening or until labor was established. Endpoints for successful cervical ripening was achievement of Bishop score of nine or greater, and for labor induction reaching the active phase of labor in the first 24 h. The rates of success, duration of first and second stages of labor, type of delivery, significant side effects, and neonatal outcome were measured and compared between the two study groups. Two hundred and fifty-one patients were randomized in two groups--126 received 50 microg and 125 received 25 microg misoprostol. Demographics of the two study groups were similar.

RESULTS

Patients in the 50 microg group had a shorter first stage (848 min vs. 1,122 min, P < 0.007), shorter induction-to-vaginal delivery interval (933 min vs. 1,194 min, P < 0.013), decreased incidence of oxytocin augmentation (53.9% vs. 68%, P < 0.015), and decreased total units of oxytocin (2,763 mU vs. 5,236 mU, P < 0.023), but there was a higher hyperstimulation rate (19% vs. 7.2%, P < 0.005).

CONCLUSIONS

Successful induction rate, delivery types, and fetal outcome were similar in both groups. Although the rate of vaginal delivery and neonatal outcome were similar in both groups, the 50 microg regimen had shorter first and second stages of labor, and a higher hyperstimulation rate that was easily manageable, allowing for flexibility in using the higher dose in low-risk pregnancies.

Adapting to managed care by becoming a learning organization

In the tumultuous and chaotic environment of managed health care, hospital-based mental health providers need to change in fundamental ways. The traditional view of mental health organizations is a professional-bureaucratic one where actions and outcomes of planning are thought to be highly predictable. The author proposes an alternative paradigm for viewing mental health provider organizations, one based on learning theory, which accepts that the future is unknowable because of its complexity and the probabilistic nature of the world. Within this perspective, mental health care providers need to become "learning organizations" to successfully adapt to the new and evolving conditions.

Efficacy of zidovudine and human immunodeficiency virus (HIV) hyperimmune immunoglobulin for reducing perinatal HIV transmission from HIV-infected women with advanced disease: results of Pediatric AIDS Clinical Trials Group protocol 185

Pediatric AIDS Clinical Trials Group protocol 185 evaluated whether zidovudine combined with human immunodeficiency virus (HIV) hyperimmune immunoglobulin (HIVIG) infusions administered monthly during pregnancy and to the neonate at birth would significantly lower perinatal HIV transmission compared with treatment with zidovudine and intravenous immunoglobulin (IVIG) without HIV antibody. Subjects had baseline CD4 cell counts </=500/microL (22% had counts <200/microL) and required zidovudine for maternal health (24% received zidovudine before pregnancy). Transmission was associated with lower maternal baseline CD4 cell count (odds ratio, 1.58 per 100-cell decrement; P=.005; 10.0% vs. 3.6% transmission for count <200 vs. >/=200/microL) but not with time of zidovudine initiation (5.6% vs. 4.8% if started before vs. during pregnancy; P=. 75). The Kaplan-Meier transmission rate for HIVIG recipients was 4. 1% (95% confidence interval, 1.5%-6.7%) and for IVIG recipients was 6.0% (2.8%-9.1%) (P=.36). The unexpectedly low transmission confirmed that zidovudine prophylaxis is highly effective, even for women with advanced HIV disease and prior zidovudine therapy, although it limited the study's ability to address whether passive immunization diminishes perinatal transmission.

Impact of a risk-based prevention policy on neonatal group B streptococcal disease

OBJECTIVE

Neonatal group B streptococcal infections can be prevented by intrapartum antibiotic prophylaxis. Beginning in 1992, women with obstetric risk factors at University of Miami-Jackson Memorial Medical Center were targeted to receive intrapartum antibiotic prophylaxis. We evaluated these preventive efforts.

STUDY DESIGN

A case was defined as isolation of group B streptococci from a sterile site in an infant <7 days old born during the study period, 1992-1995. We reviewed systematic samples of women with preterm delivery and prolonged rupture of membranes to assess use of intrapartum antibiotic prophylaxis.

RESULTS

Group B streptococcal cases declined from 1.7 cases/1000 live births to 0.2 cases/1000 live births (Poisson regression, P =.002). Intrapartum antibiotic prophylaxis use increased from 13% of preterm deliveries in 1992 to 42% in 1995, and from 20% of deliveries with prolonged rupture of membranes in 1992 to 72% in 1995 (chi2 test for linear trend P =.007 and P <.001, respectively).

CONCLUSION

Provision of intrapartum antibiotic prophylaxis on the basis of risk factors was associated with decreased group B streptococcal disease.

The importance of early weight gain in the intrauterine growth and birth weight of twins

OBJECTIVE

It was our objective to evaluate the association between early maternal weight gain (before 20 weeks), midpregnancy weight gain (20-28 weeks), and late pregnancy weight gain (28 weeks to birth) with fetal growth and birth weight in twins.

STUDY DESIGN

This historic cohort study was based on 1564 births of live twins >/=28 weeks' gestation from Baltimore, Maryland, Miami, Florida, Charleston, South Carolina, and Ann Arbor, Michigan.

RESULTS

Early fetal growth was affected only by smoking and chorionicity. Factors in models of both mid and late fetal growth included maternal age, pregravid weight, parity, rates of early pregnancy and midpregnancy maternal weight gain, smoking, and pre-eclampsia. Increased midpregnancy fetal growth was associated with early maternal weight gain (10.91 g/wk per pound per week) and midpregnancy maternal weight gain (15.89 g/wk per pound per week). Increased late fetal growth was associated with early maternal weight gain (16.86 g/wk per pound per week) and midpregnancy maternal weight gain (23.88 g/wk per pound per week). Increased birth weight was associated with early (283.02 g per pound per week), mid (163.58 g per pound per week), and late (69.76 g per pound per week) maternal weight gains.

CONCLUSIONS

These findings confirm the importance of early maternal weight gain in twin fetal growth and birth weight.

Traumatic vertebral arterial dissection and vertebrobasilar arterial thrombosis successfully treated with endovascular thrombolysis and stenting

A case of traumatic extracranial vertebral arterial dissection leading to vertebrobasilar thrombosis and respiratory compromise requiring mechanical ventilation was managed with intraarterial thrombolysis and stenting of the vertebral intimal dissection. In contrast to similar, previously reported cases, this critically ill patient made a full recovery, returning to his job as a secondary school teacher.

Lymphoid lesions of the gastrointestinal tract: a histologic, immunophenotypic, and genotypic analysis of 49 cases

The diagnosis of gastrointestinal (GI) lymphoid infiltrates can be challenging when based only on conventional microscopic assessment. When marked cytologic atypia is present, a diagnosis of malignant neoplasm is readily made; however, the distinction between a low-grade malignant neoplasm and a reactive process is much more difficult. If unfixed tissue is available, immunohistologic or genotypic methods that are usually aimed at defining B-lymphocytic monotypism can be applied. However, paraffin-embedded tissue has generally been deemed unsuitable for these techniques. We assessed the value of a panel of immunohistochemical stains and a seminested polymerase chain reaction (PCR) for the analysis of lymphoid infiltrates in routinely processed GI biopsy specimens from 49 archival cases, including morphologically benign, indeterminate, and overtly malignant lesions. Clinical outcome was used as the retrospective diagnostic standard; end points were death (of lymphomatous disease or otherwise) and clinical evidence of lymphoma. According to light microscopic criteria, 19 cases were classified as benign, 17 as malignant, and 13 as atypical. Immunophenotyping correctly identified 28 of 31 benign and 14 of 18 malignant lesions (7 cases had an indeterminate immunoprofile). Genotypic analysis correctly identified 12 of 18 malignant and 29 of 31 benign lesions, but spurious monoclonal bands were produced by PCR amplification of 2 of the latter 31 cases. No single technique exists for correct categorization of all paraffin-embedded specimens of GI lymphoid infiltrates. We recommend a sequential approach to the use of available diagnostic modalities.

Morphologic observations in a case of lethal variant (type I) metatropic dysplasia with atypical features: morphology of lethal metatropic dysplasia

Metatropic dysplasia accounts for approximately 5% of cases recorded by the International Skeletal Dysplasia Registry, with a single recorded lethal case. Four forms of the disease are currently recognized: type I, lethal autosomal recessive form; type II, nonlethal autosomal recessive form with survival to childhood; type III, autosomal dominant form with typical features, and type IV, a mild form with uncertain inheritance. The literature contains few well-documented reports of the histopathologic findings in metatropic dysplasia. In this report, we present the radiologic and histopathologic features in a cas e of type I metatropic dysplasia, with the unusual features of a persist ent tail, unique lung dysmorphology, and thyroidal agenesis.

Familial adenomatous polyposis: from bedside to benchside

Familial adenomatous polyposis (FAP) is a dominantly inherited cancer-predisposition syndrome with an incidence of between 1:17,000 and 1:5,000. The condition has been causally linked to mutation of the adenomatous polyposis coli (APC) gene located at 5q21. Virtually all mutations in the APC gene are truncating mutations, resulting in loss of function of the APC protein. Spontaneous germline mutation of this gene occurs frequently and accounts for the high incidence of FAP. The gene is somatically mutated at an early point in the colorectal adenoma-carcinoma progression. Somatic mutations of the APC gene are also frequently observed in a variety of other human carcinomas. Isolation of the APC gene has led to the recognition of genotype-phenotype correlations and, together with protein studies, has helped to elucidate the structure and function of the APC protein. This report aims to take the reader from a clinical appreciation to a molecular understanding of FAP.

Cervical intraepithelial neoplasia III shows frequent allelic loss in 3p and 6p

We have shown previously that a significant number of invasive cervical cancers (ICC) have nonrandom chromosomal losses in 3p, 6p, 11q, 2q, 6q, and 19q, thereby suggesting that genes involved in the suppression of tumor development or progression are located in these regions. Cervical intraepithelial neoplasia (CIN) III is considered the precursor lesion for ICC of squamous type and occurs frequently with ICC of glandular type. In an effort to define which chromosomal losses are present in the precursor lesions, we identified CIN III lesions from 24 ICC treated by radical hysterectomy. Thirty-three CIN III associated with 22 squamous carcinomas and 2 adenocarcinomas were carefully microdissected from the paraffin-embedded sections. The whole genomic DNA from CIN III was amplified with short random primers. DNA from ICC, CIN III, and normal tissue was analyzed at the six chromosomal regions with polymorphic markers. Thirty-eight percent of hysterectomy specimens had loss of heterozygosity (LOH) in at least one of the CIN III lesions from each case. Loss occurred in 30% of cases in 3p14.1-12 (37% for associated ICC), 21% in 6p23 (33%), 14% in 2q33-37 (27%), 0 in 11q23.3 (33%), 4% in 19q13.4 (13%), and 0 in 6q21-23.3 (18%). These results suggest that mutations in 3p and 6p are important early in tumorigenesis, whereas 11q and 6q contain genes important later in tumor progression. Invasive and preinvasive cervical lesions appear to develop from multifocal genetic events since consistent losses do not occur within all precursor lesions in the same patient.

Fetal bradycardia secondary to magnesium sulfate therapy for preterm labor. A case report

BACKGROUND

Alterations in fetal heart rate variability and baseline may be seen with maternal administration of magnesium sulfate. In this case, a dose-related decrease in the baseline fetal heart rate was observed in association with magnesium sulfate administration.

CASE

A primiparous woman was given parenteral magnesium sulfate for preterm labor. After tocolytic administration, the fetal heart rate baseline decreased to 110 beats per minute (bpm) from its initial rate of 140 bpm, although good variability was maintained. Increasing the dosage was accompanied by a further drop in the baseline heart rate, to 100 bpm. Fetal echocardiography was normal except for sinus bradycardia. Stopping magnesium sulfate administration was accompanied by a return to the pretherapy baseline heart rate. The pregnancy progressed without any further complications, and a healthy infant was delivered three weeks later.

CONCLUSION

Maternal administration of magnesium sulfate may be associated with a profound decrease in the baseline fetal heart rate, resulting in fetal sinus bradycardia.

Critical periods of maternal weight gain: effect on twin birth weight

OBJECTIVE

Our purpose was to evaluate the association between maternal weight gain and twin birth weight.

STUDY DESIGN

This historic cohort study was based on 646 live-born twin births of > or = 28 weeks from Baltimore, Maryland, Miami, Florida, and Ann Arbor, Michigan. The sum of twin-pair birth weight was modeled as a function of either net maternal weight at delivery or rates of maternal weight gain with use of multiple regression.

RESULTS

Birth weight was significantly associated with weight gain before 20 weeks in underweight women, before 20 weeks and after 28 weeks in overweight women, and during all three gestational periods in normal-weight women. Weight gain before 20 weeks had the largest effect on infants of underweight women, less of an effect on infants of normal-weight women, and half as much effect on infants of overweight women. Weight gain after 28 weeks significantly affected the infant birth weights of normal-weight and overweight women, but the effect was half as great among infants of the latter group.

CONCLUSIONS

These findings suggest that weight gain during critical periods of gestation significantly influences twin birth weight; these critical periods vary by maternal pregravid weight status.