A case-control study of unexplained antepartum stillbirths.

OBJECTIVE: To ascertain factors that will identify women who are at increased risk of unexplained antepartum stillbirth. DESIGN: Matched case-control study. The cases and controls were initially analysed as a whole group and again after dichotomizing into those of low birthweight (< 2500 g) and those of normal birthweight (> or = 2500 g). SETTING: Western Australia 1980-1983. SUBJECTS: Unexplained antepartum stillbirths of > or = 1000 g birthweight (cases) and liveborn infants individually matched for year of birth, plurality, sex and birthweight of infant and race of mother (controls). RESULTS: The case pregnancies had more polyhydramnios (OR 10.83, 95% CI 2.41-48.69) and cord problems (OR 6.57 95% CI 1.36-31.75) than the controls but, paradoxically, other obstetric and medical complications were less common in the cases. The association with polyhydramnios persisted when the analysis was confined to those with low birthweight. With normal birthweight fetal distress was more frequent in the cases (OR 3.65 95% CI 1.36-9.80) but there were few other differences. CONCLUSIONS: The clinical and diagnostic systems currently in use are unable to identify many fetuses at risk of death. Decreases in the rate of unexplained antepartum stillbirths await the discovery of new preventable causes, or of innovations in clinical or laboratory aspects of obstetric care.     

A case-control study of stillbirths in northeast Brazil.

An institution based case-control study to determine risk factors for stillbirths was conducted in the city of Natal, NE Brazil, where 90% of deliveries take place in health facilities. Two hundred thirty-four singleton stillborn cases were compared to 2555 liveborn singleton control infants of normal birth-weight and gestational age. Information was obtained by postnatal interview and anthropometry, and review of medical records. Univariate analyses revealed a large number of potential risk factors, but after adjustment by logistic regression only six factors remained significantly associated with stillbirth. These were low maternal weight, less than or equal to 50 kg and a history of pregnancy loss, both with odds ratios (OR) of 1.8, inadequate prenatal care defined as less than five visits (OR = 1.9), gestational complications (OR = 14.2), intrapartum complications (OR = 2.0), and congenital malformations (OR = 8.7). There was also an increased risk of stillbirth among older mothers who smoked (OR = 1.4), and evidence of an interaction between smoking and complications of pregnancy. From the public health perspective, the most important factors amenable to intervention were inadequate prenatal care and antenatal or intrapartum complications which were associated with substantial attributable risks (23.8%, 35.2%, and 10.2%, respectively). Thus, in this population, future reductions of the high stillbirth rate (27.2 per 1000 births) will largely depend on the coverage, utilization, and quality of antenatal and intrapartum care.     

Recurrent stillbirths: a matched case-control study of unexplained stillbirths at term.

The aim of this study was to assess the recurrent risk of an unexplained stillbirth at term. A total of 75 women who delivered stillbirths were matched for maternal age and parity with 75 controls. After excluding explained stillbirths, matched cases and controls were compared for maternal age, length of gestation, birth weight and 'interval to next birth'. The main outcome measure was the frequency of recurrence of a stillbirth. Both groups were similar for maternal age and length of gestation. Birth weight was marginally different (odds ratio (OR) = 0.997, 95% confidence interval (CI) 0.996, 0.999) and 'interval to next birth' was longer (OR = 1.08, 95% CI 1.00, 1.17). There were no stillbirths in cases and controls at follow-up. We conclude that a woman who has had an unexplained stillbirth at term has no greater risk of recurrence than a matched control. However, the 'interval to next birth' was significantly longer.     

Antenatal and intrapartum antecedents of cerebral palsy: a case-control study

AIM: To identify antenatal and intrapartum factors contributing to the aetiology of cerebral palsy (CP). METHODS: A case-control study using moderate/severe cases of cerebral palsy identified from the Victorian Cerebral Palsy Register and two controls per case identified through the Victorian Perinatal Data Collection Unit. RESULTS: A number of previously identified risk factors for CP were confirmed in our data. New observations were (in specific sub-groups): protective effects of mother's negative Rhesus status, cigarette smoking at the first visit and episiotomy and an increased risk of CP associated with an abnormal antenatal cardiotocograph. CONCLUSIONS: Although the result of the deliberate investigation of specific aspects of the antenatal and intrapartum period identified from a pilot study, our new findings must be interpreted with caution as they were not all based on specific a priori hypotheses, although some had been examined by other investigators. We would encourage their evaluation in other data sets.     

The intrapartum CTG prior to neonatal encephalopathy at term: a case-control study

Objective To compare cardiotocograph (CTG) records during labour in cases of neonatal encephalopathy and matched controls.
Design Case—control study.
Setting Metropolitan area of Perth, Western Australia.
Subjects Term deliveries complicated by neonatal encephalopathy and controls matched for sex, hospital, time of birth, day of week of birth and maternal health insurance.
Main outcome measures Low fetal heart rate (FHR) variability, FHR accelerations, late decelerations, total Kreb's score and FIGO classification of CTG records.
Results The neonatal encephalopathy group had significantly more abnormal CTG records (89%) classified according to FIGO, although 52% of control CTG records were also abnormal. CTG records from cases developed significant differences in terms of absence of FHR accelerations and low FHR variability, but not late decelerations, prior to delivery.
Conclusion Given the low incidence of neonatal encephalopathy in this study (7 per 1000) the predictive value of an abnormal CTG record is clinically unhelpful. However, the changes in the FHR in such cases suggest a greater disturbance of fetal (rest—activity) behaviour during labour.     

Prophylactic intrapartum amnioinfusion for patients with oligohydramnios. A prospective randomized study.

This prospective study evaluated whether prophylactic saline amnioinfusion among patients with amniotic fluid index (AFI) < or = 5.0 cm decreases the incidence of adverse fetal outcomes. Randomization of 53 patients with decreased AFI at term, resulted in 21 patients' receiving prophylactic saline amnioinfusion early in labor, prior to development of an abnormal fetal heart rate tracing. For the treatment group the mean AFI on admission was 3.0 cm, and the postamnioinfusion AFI was 8.9 cm. For 32 comparison (noninfusion) patients, the mean AFI was 2.9 cm; the group consisted of 17 patients randomized to receive no amnioinfusion (control group) and 15 patients who refused to participate in the study. There was no statistically significant difference between the amnioinfused and nonamnioinfused patients with regard to age, parity, gestational age, AFI at admission or duration of first or second stage of labor. Amnioinfusion resulted in no statistically significant reduction in the incidence of recurrent variable decelerations/bradycardia (26.3% vs. 46.6%), intrapartum resuscitation with terbutaline (5.2% vs. 10.0%), cesarean section for fetal distress (9.5% vs. 9.3%), fetal-acidosis (10.5% vs. 12.0%) or Apgar scores < 7 at five minutes (5.2% vs. 0%) in patients with oligohydramnios.     

A population-based case-control teratologic study of nalidixic acid.

OBJECTIVE: Quinolones, mainly nalidixic acid, are frequently used in Hungary to treat bacterial infections in pregnant women, but so far no controlled epidemiological studies of congenital abnormalities among infants born to women treated with nalidixic acid during pregnancy have been reported. METHODS: The analysis of oral nalidixic acid use during pregnancy in the mothers of cases with congenital abnormalities and in their matched population controls without congenital abnormality was carried out in the population-based dataset of the Hungarian Case-Control Surveillance of Congenital Abnormalities between 1980 and 1996. The study included 22865 women who had newborns or fetuses with congenital abnormalities, and 38151 pregnant women who had newborn infants without any defects (controls). RESULTS: In the case group, 242 (1.1%) and in the control group, 377 (1.0%) pregnant women were treated with nalidixic acid (crude OR: 1.1 with 95% CI: 0.9-1.3). Seventeen different congenital abnormality groups were evaluated and a higher prevalence of pyloric stenosis was found in seven case infants born to mothers who received nalidixic acid treatment during the last months of pregnancy (adjusted OR: 11.0 with 95% CI: 1.3-91.4). CONCLUSIONS: Treatment with nalidixic acid during pregnancy may increase the risk of pyloric stenosis, though the chance effects cannot be excluded.     

A case-control study of the effects of birth by caesarean section on intrapartum and neonatal mortality among twins weighing 1500-2499 g

The aim of this nationally-based, matched case-control study was to assess the impact of birth by caesarean section on intrapartum, and neonatal mortality among twins weighing 1500-2499 g, born in Sweden between 1973 and 1983. By using data held at the National Medical Birth Registry, Stockholm, 91 such pregnancies (study cases) where one or both twins died were identified. For each case, two controls (in all 182 pregnancies) were allotted at random from the rest of the twin pregnancies, with similar birthweight (+/- 100 g) and year of delivery (+/- 1 year). The number of twins that died was reduced from 73 during the first four years to 22 between 1977 and 1980, and to 6 during the last 3 years of the study period. Almost a quarter (23.1%) had a lethal malformation. The caesarean section rate increased during the study period, but did not differ between cases and controls (chi 2 = 1.0; P greater than 0.05). The analysis could not confirm a significant difference between cases and controls regarding the number of infants born vaginally in non-vertex presentation (chi 2 = 0.1; P greater than 0.05). The results of this study appear to indicate that birth by caesarean section was not a major factor related to the improved fetal outcome.     

A case-control study of uterine perforations documented at laparoscopy.

A case-control analysis was done of 19 cases of uterine perforations which occurred during laparoscopic sterilization at Gardy Memorial Hospital in Atlanta, between February 1, 1974, and January 31, 1976. The over-all perforation rate, 30.4 per 1,000 procedures, is three to 30 times that commonly reported for dilatation and suction or sharp curettage (D&C) of the uterus. Case women were 10.4 times more likely than control women to combine two of the following three characteristics: age greater than 34, parity greater than 4, and obesity greater than 20 per cent above the ideal body weight for height. Surgeons with fewer months of formal Ob/Gyn training were no more likely than their relatively more experienced colleagues to perforate the uterus. No other risk factors were delineated. It is believed that the perforation rate, higher in this study than in earlier ones, reflects better ascertainment of perforations. The bleeding site was always visualized with the laparoscope in this series.     

Acute intrapartum twin-twin transfusion. A case report.

A rare case of acute intrapartum twin-twin transfusion occurred. The well-recognized criteria of long-standing chronic twin-twin transfusion were absent. Although a cesarean section was performed for obstetric reasons, the hyperperfused twin, A, died intrapartum. Twin B, the hypoperfused twin, although liveborn, died neonatally of renal failure attributed to renal cortical necrosis as a sequel to hypotension.     

A prospective study of microbial infection in stillbirths and early neonatal death

No morphologic cause of death was found in 67.8% of 33 perinatal deaths. The mothers had experienced a previous loss in 48% of cases. Inflammation occurred in 65.6% of the cases of perinatal death compared to 4% of a control group (p less than 0.001) and in 73.1% of organism-positive cases of perinatal death compared to 7.1% of organism-positive cases of the control group (p less than 0.001). Incidence of maternal fever or prolonged membrane rupture was not statistically significant. Bacteria were present in 33.3% of the cases of perinatal death (not significant), with more pathogenic strains occurring in this group (p = 0.0028); 75.0% had inflammation compared to 0% of the control group (not significant). Genital mycoplasmas were detected in 78.8% of cases of perinatal death compared to 32.3% of control cases (p less than 0.001). Positive cultures (p = 0.0142) and elevated antibody titers in the fetus or neonate (p = 0.00052) or in the mother (p = 0.0122) occurred significantly more often than in control cases. Inflammation occurred in 78.9% of mycoplasma cases (p = 0.00032); incidences of maternal fever and prolonged membrane rupture were not significantly different. In perinatal death cases 20% had evidence of viruses, and 3.2% had evidence of chlamydia. Evidence of mixed microorganisms occurred in 46% of cases of perinatal death. However, 78.6% (11 of 14) with only one organism had Ureaplasma urealyticum (33.3% overall). Of the Ureaplasma-positive cases, 72.7% had inflammation, 45.5% had fever, and only 18.2% had prolonged membrane rupture compared to 28.6%, 0%, and 16.6%, respectively, in a negative-microorganism group with perinatal deaths. Our observations strongly support the concept that infection is a major cause of perinatal death and that genital mycoplasmas play a significant role.     

A case-control study of the effects of birth by caesarean section on intrapartum and neonatal mortality among twins weighing 1500–2499 g

Summary. . The aim of this nationally-based, matched case-control study was to assess the impact of birth by caesarean section on intrapartum, and neonatal mortality among twins weighing 1500–2499 g, born in Sweden between 1973 and 1983. By using data held at the National Medical Birth Registry, Stockholm, 91 such pregnancies (study cases) where one or both twins died were identified. For each case, two controls (in all 182 pregnancies) were allotted at random from the rest of the twin pregnancies, with similar birthweight (±100 g) and year of delivery (±1 year). The number of twins that died was reduced from 73 during the first four years to 22 between 1977 and 1980, and to 6 during the last 3 years of the study period. Almost a quarter (23.1%) had a lethal malformation. The caesarean section rate increased during the study period, but did not differ between cases and controls (  χ²= 1.0  ;   P >0.05  ). The analysis could not confirm a significant difference between cases and controls regarding the number of infants born vaginally in non-vertex presentation (  χ²= 0.1  ;   P >0.05  ). The results of this study appear to indicate that birth by caesarean section was not a major factor related to the improved fetal outcome.     

A case-control study of epithelial ovarian cancer

With data from a study of 296 patients with primary epithelial ovarian cancer and 343 patients hospitalized because of other conditions, we estimated ovarian cancer risk in accordance with reproductive and other factors. Risk was greatest among women of lower parity, especially among women who said they planned to have children but could not. The protective effect of oral contraceptives seen in other studies was observed only in subgroups of our study population. Women who had breastfed their children had decreased risk, but the number of months of breastfeeding was not related to risk. Incomplete pregnancies did not provide the protection seen for live births. A family history of ovarian cancer and a medical history of breast cancer were both strong risk factors. None of the nonreproductive factors that we examined, including childhood illnesses, tobacco and alcohol consumption, obesity, and selected adult diseases, was convincingly associated with risk.     

Balneotherapy with arsenical-ferruginous water in chronic cervico-vaginitis. A case-control study

BACKGROUND: The aim of this study was to evaluate the efficacy and tolerability of vaginal irrigations with arsenical-ferruginose water from the spa at Terme di Levico in chronic cervico-vaginitis in order to assess the validity of balneotherapy in improving the symptoms and quality of life of patients. METHODS: An open comparative study was performed in 30 patients with symptoms attributable to aspecific chronic vaginitis (in child-bearing age) or vulvovaginal dystrophy (perimenopausal age). Twenty patients (Group A) received balneotherapy and 10 (Group B) were treated with placebo vaginal suppositories. All patients were required to fill in a questionnaire on symptoms. A thorough gynecological examination was performed, together with a Pap-test and vaginal secretion sample for bacterioscopic and microbiological tests. The same tests were repeated at the end of treatment. RESULTS: Post-treatment results showed a general reduction in the extent of gynecological symptoms reported by patients. A statistically significant reduction was only observed in patients receiving balneotherapy for the following symptoms: vaginal burning , vulvar burning , vaginal itch , vulvar itch , leukorrhea . An analysis of the cytological tests performed in patients enrolled in the study highlighted a high prevalence of phlogistic type findings, often in association with varying degrees of atrophy in postmenopausal patients. Those patients suffering from chronic vaginitis undergoing balneotherapy showed a reduction in the prevalence of phlogistic findings after treatment. CONCLUSIONS: Treatment with arsenical-ferruginose water led lo a marked reduction in the subjective symptoms reports by the study population (particular evident in patients with chronic leukorrhea), as was confirmed by objective signs (clinical, cytological and microbiological) of phlogosis. This was accompanied by excellent tolerability. These results justify the use of balneotherapy, according to the classic techniques and methods, in chronic cervicovaginal phlogistic processes.     

A case-control study of oxidized low density lipoproteins and preeclampsia risk.

Diffuse vascular endothelial dysfunction, secondary to oxidative stress, is an important pathological feature of preeclampsia. Oxidative conversion of low density lipoproteins (LDL) to oxidized-LDL (Ox-LDL) is considered an important step in transforming macrophages into lipid-laden foam cells destined to develop into early atherosclerotic-like lesions. In our study of 95 women with preeclampsia and 100 controls, we evaluated the association between maternal plasma Ox-LDL concentrations and preeclampsia risk. Ox-LDL concentrations were measured using a solid phase two-site enzyme immunoassay. Plasma lipids were measured using standard enzymatic procedures. We used logistic regression to estimate odds ratios (OR) and 95% confidence intervals (CI) adjusted for confounders. Plasma Ox-LDL concentrations were positively correlated with cholesterol, triglyceride (TG), and LDL concentrations in cases and controls, (Spearman's r ranging from 0.39-0.48, p-values all <0.01). There was no evidence of an increased risk of preeclampsia across increasing quartiles of Ox-LDL. The ORs for successive quartiles, with the lowest as the reference group, were as follows: 1.0, 1.1, 0.6, and 1.2. Women with extremely high concentrations of Ox-LDL (> or =73 U/L, the upper decile), as compared with those with lower values (<73 U/L) had a 2.7-fold increased risk of preeclampsia (95% CI 1.0-6.8). Women with high Ox-LDL and high TG concentrations (> or =284 mg/dl), as compared with those without these two factors, had a 9.6-fold increased preeclampsia risk (95% CI 2.0-45.6). Elevated Ox-LDL, particularly in conjunction with elevated TG, appears to be a risk factor of preeclampsia.