Relative Risk Of Fetal Death Research Articles

The Contribution of Multiple Pregnancies in Stillbirths in Greece: A Time-Trend Analysis.

Introduction Multiple pregnancy is an established risk factor for fetal death. This study aimed to examine the impact of multifetal pregnancies on stillbirth rates (SBRs) in the Greek population. Methods Data on live births and stillbirths by multiplicity were derived from the Hellenic Statistical Authority, covering a 65-year period from 1957 to 2021. The SBRfor multiple and single gestations, and the population attributable risk (%) (PAR (%)) stillbirth attributable to multifetal gestationswere calculated, and temporal trends were assessed using joinpoint regression analysis, with annual percentage changes (APC) and 95% confidence interval (95% CI). Results In the period 1957-2021, multiple pregnancies accounted for 9.4% of total stillbirths in Greece and the overall relative risk of fetal death among multifetal gestations was 3.34, in comparison with singletons. The SBR in multiple births remained unchanged from 1957 to 1976 and showed downward trends from 1976 to 2021 (APC = -3.0, 95% CI: -3.4 to -2.7, p < 0.001). PAR (%), after two decades of stability, showed an increasing trend over the period 1975-2011 (APC = 3.4, 95% CI: 2.8 to 4.0, p < 0.001), which was reversed in the more recent decade 2011-2021 (APC = -6.1, 95% CI: -9.6 to -2.5, p = 0.001), with PAR (%) decreasing from a historical high of 19.3% in 2012 to 8.6% in 2021. Conclusion The high incidence of multiple births has a considerable impact on stillbirth rates in the Greek population. The recent downward trends of SBR and PAR (%) of multiple gestations are encouraging, however more measures and targeted interventions are needed to improve perinatal outcomes in multifetal gestation.

Risk of fetal death with preeclampsia.

To estimate gestational age-specific risks of fetal death in pregnancies complicated by preeclampsia. Population-based cohort study comprising all singleton births (N=554,333) without preexisting chronic hypertension recorded in the Norwegian Medical Birth Registry from 1999 to 2008. Additional data come from a subset of preeclamptic pregnancies enrolled in the Norwegian Mother and Child Cohort Study with available medical records (n=3,037). The risk of fetal death, expressed per 1,000 fetuses exposed to preeclampsia, was calculated using a life table approach. Preeclampsia was recorded in 3.8% (n=21,020) of all pregnancies. Risk of stillbirth was 3.6 per 1,000 overall and 5.2 per 1,000 among pregnancies with preeclampsia (relative risk 1.45, 95% confidence interval [CI] 1.20-1.76). However, relative risk of stillbirth was markedly elevated with preeclampsia in early pregnancy. At 26 weeks of gestation, there were 11.6 stillbirths per 1,000 pregnancies with preeclampsia compared with 0.1 stillbirths per 1,000 pregnancies without (relative risk 86, 95% CI 46-142). Fetal risk with preeclampsia declined as pregnancy advanced, but at 34 weeks of gestation remained more than sevenfold higher than pregnancies without preeclampsia. For clinical purposes, the fetal risk of death associated with preeclampsia begins when preeclampsia becomes clinically apparent. Using a method that takes into account the clinical diagnosis of preeclampsia and the population of fetuses at risk, we find a remarkably high relative risk of fetal death among pregnancies diagnosed with preeclampsia in the preterm period. II.

Antenatal care packages with reduced visits and perinatal mortality: a secondary analysis of the WHO Antenatal Care Trial

BackgroundIn 2001, the WHO Antenatal Care Trial (WHOACT) concluded that an antenatal care package of evidence-based screening, therapeutic interventions and education across four antenatal visits for low-risk women was not inferior to standard antenatal care and may reduce cost. However, an updated Cochrane review in 2010 identified an increased risk of perinatal mortality of borderline statistical significance in three cluster-randomized trials (including the WHOACT) in developing countries. We conducted a secondary analysis of the WHOACT data to determine the relationship between the reduced visits, goal-oriented antenatal care package and perinatal mortality.MethodsExploratory analyses were conducted to assess the effect of baseline risk and timing of perinatal death. Women were stratified by baseline risk to assess differences between intervention and control groups. We used linear modeling and Poisson regression to determine the relative risk of fetal death, neonatal death and perinatal mortality by gestational age.Results12,568 women attended the 27 intervention clinics and 11,958 women attended the 26 control clinics. 6,160 women were high risk and 18,365 women were low risk. There were 161 fetal deaths (1.4%) in the intervention group compared to 119 fetal deaths in the control group (1.1%) with an increased overall adjusted relative risk of fetal death (Adjusted RR 1.27; 95% CI 1.03, 1.58). This was attributable to an increased relative risk of fetal death between 32 and 36 weeks of gestation (Adjusted RR 2.24; 95% CI 1.42, 3.53) which was statistically significant for high and low risk groups.ConclusionIt is plausible the increased risk of fetal death between 32 and 36 weeks gestation could be due to reduced number of visits, however heterogeneity in study populations or differences in quality of care and timing of visits could also be playing a role. Monitoring maternal, fetal and neonatal outcomes when implementing antenatal care protocols is essential. Implementing reduced visit antenatal care packages demands careful monitoring of maternal and perinatal outcomes, especially fetal death.

Prepregnancy Obesity and Fetal Death: A Study Within the Danish National Birth Cohort

More than half of women in the United States who are 20 to 39 years of age are overweight or obese. A similar but somewhat delayed pattern is seen in Europe. Prepregnancy obesity—defined as a body mass index (BMI) of 30 kg/m2 or higher—has been associated with severe complications of pregnancy and delivery, including stillbirth, which accounts for more than half of all perinatal deaths. The investigators used data from the Danish National Birth Cohort of 54,505 pregnant women to examine the association between a high prepregnancy BMI and fetal death while controlling for several parameters. The incidence of obesity in this population was 8%. Another 19% of women were overweight (BMI of 25–29.9 kg/m2), 68% had normal body weight (BMI 18.5–25.0 kg/m2), and 5% were underweight (BMI less than 18.5 kg/m2). The overall risk of stillbirth in this study was 2.8 per 1000. Compared with women of normal weight, those who were obese or overweight were slightly younger, smoked more, drank less alcohol, and exercised less. Preeclampsia, other hypertensive conditions, and gestational diabetes all were more frequent in obese and overweight women. The relative risk of fetal death rose with gestational age in these groups. After 14 weeks gestation, the expected drop in fetal deaths across gestation was more marked in normal-weight women than in the obese and overweight groups. The adjusted relative risk of stillbirth in obese women was 360% higher when pregnancy lasted more than 280 days. Neither parity nor smoking altered the apparent effect of BMI on fetal death. Adjusted risk estimates changed only minimally after excluding women with preeclampsia, other hypertensive disorders, or diabetes. Overweight women still had twice the risk of stillbirth compared with normal-weight women, and the risk increased 240% for obese women. In addition, obese and overweight women were relatively likely to have unexplained intrauterine deaths and deaths resulting from placental dysfunction after adjusting for possible confounding factors. In this large population of pregnant women, those who were obese before pregnancy were likelier than others to experience fetal death as gestation advanced. Placental dysfunction may be partly responsible. It seems advisable to encourage obese women who want to become pregnant to lose weight.

Association Between Congenital Anomalies and Paternal Exposure to Agricultural Pesticides Depending on Mother’s Employment Status

We analyzed the association between fetal death from congenital anomalies and paternal agricultural occupation in mothers who were employed and in housewives. The data consist of individual records from the Spanish Birth Register (1995-1999). The adjusted relative risk of fetal death in agricultural workers compared with nonagricultural was 1.24 (95% confidence interval = 0.38- 4.02) in mothers who were employed and 1.68 (95% confidence interval = 1.03-2.73) in housewives. The risk of fetal death in the offspring of agricultural workers exposed to pesticides around the time of conception was higher than in the offspring of nonagricultural workers in mothers who were housewives but not in mothers who worked outside the home.

Maternal Age and Risk of Fetal Death in Singleton Gestations: United States, 1995???2000

Women less than 20 or more than 35 years of age account for at least one fourth of all births in the United States today. Advancing maternal age could increase the risk of fetal death, warranting antenatal testing. The risk of fetal death was examined retrospectively in a cohort of 21,610,873 singleton births taking place at or after 24 weeks gestation. The investigators analyzed U.S. perinatal mortality data on linked birth-infant deaths in the years 1995 to 2000. Eligible births numbered 21,610,873. Women less than 20 years of age and those aged 35 and older made up 12.6% and 11.4% of all births, respectively. Proportions of primigravid women, blacks, unmarried subjects, and smokers declined as maternal age increased. The overall rate of fetal death at and after 24 weeks gestation was 2.7 per 1000 total births. The lowest rates of fetal death were in women aged 25–29 and 30–34 years (2.4 per 1000 births). The adjusted relative risk of fetal death was not increased in young women, but did increase progressively for women aged 35–39 and 40–44 years, reaching 2.4 in women 45–49 years of age. The association of age with fetal death was noted in both blacks and whites but, at ages 45–49 years, was stronger for blacks. Relative risk values were 2.4% for chronic hypertension, 1.5% for pregnancy-induced hypertension, 1.9 for diabetes, and 4.4 for small-for-gestational age cases. The overall rate of fetal death at and after 32 weeks gestation was 1.9 per 1000 total births. The rate was lowest at ages 25–29 and 30–34 years (1.7 per 1000). These findings affirm that advanced maternal age independently increases the risk of fetal death and suggests that advanced maternal age alone could be a valid reason for antenatal fetal testing. It is not yet clear, however, whether the degree of increased risk is great enough to warrant testing.

Paternal exposure to agricultural pesticides and cause specific fetal death

Aims: To study the association between fetal death and paternal agricultural occupation in areas and time periods with different levels of use of agricultural pesticides. Methods: A total of 1...

Fever in Pregnancy and Risk of Fetal Death: A Cohort Study

Many studies of animals, including primates, indicate that hyperthermia during pregnancy is associated with fetal death and possibly lethal malformations. There are suggestions that in humans, either endogenous (febrile) hyperthermia or external heating may be linked with neural tube defects. This cohort study interviewed 24,040 women in Denmark during the first half of pregnancy to document febrile episodes in the first 16 weeks of gestation. The incidence of miscarriage or stillbirth during the 18-month study period was 4.8%. Nearly one in five women, 18.5%, reported at least one episode of fever, and about 45% of those reporting a peak temperature had had fever of 39°C or higher. Fever had lasted 2 to 3 days in a majority of women and 4 days or longer in nearly one fourth of the study group. Close to 10% of women reported more than one febrile episode. The risk of fetal death in women reporting fever in the first 16 gestational weeks was no higher than in those without fever, and this result was unchanged after adjusting for numerous factors: maternal age, parity, previous miscarriages, and the use of tobacco, alcohol, and coffee during pregnancy. When including pregnancies ending with induced abortion on indication in the fetal death group, the relative risk of fetal death in women reporting fever was 0.99 (95% CI, 0.84-1.16). There were no differences in fetal death in any trimester of pregnancy or for any specified period within the first 16 weeks. Taking the maximum temperature into account also made no difference. Neither the days of fever nor the number of febrile episodes correlated with fetal death. The lack of a relationship between early gestational fever and fetal death held when only women who were interviewed while pregnant and followed up prospectively were considered. This large-scale cohort study failed to show that fever in the first 16 weeks of pregnancy increases the risk of fetal death, and the investigators believe that pregnant women may be reassured on this point.

Fever in pregnancy and risk of fetal death: a cohort study

Hyperthermia acts as a teratogen in some animals where it can induce resorption of the fetus and fetal death. Fever during pregnancy, especially in the period of embryogenesis, is also suspected as being a risk factor for fetal death in human beings. We did a large cohort study in Denmark to investigate this possibility. We interviewed 24040 women who were recruited in the first half of pregnancy to the Danish National Birth Cohort Study, and obtained information on the number of fever incidents during the first 16 weeks of pregnancy. For each fever episode, the highest measured body temperature, duration of incident, and gestational age were recorded. Outcomes of pregnancies were identified through linkage with the Civil Registration System and the National Discharge Registry. Cox's regression with time-dependent variables was used to estimate the relative risk of fetal death, taking delayed entry into account. 1145 pregnancies resulted in a miscarriage or stillbirth (4.8%). During the first 16 pregnancy weeks 18.5% of the women experienced at least one episode of fever. However, we found no association between fever in pregnancy and fetal death before or after adjustment for known risk factors of fetal death (relative risk 0.95 [95% CI 0.80-1.13]). This finding was consistent irrespective of measured maximum temperature, duration and number of fever incidents, or the gestational time of the fever incident, and was observed for fetal death in all three trimesters of pregnancy. We found no evidence that fever in the first 16 weeks of pregnancy is associated with the risk of fetal death in clinically recognised pregnancies.

Pregnancy in women with reflux nephropathy

Reflux nephropathy is one of the most prevalent renal diseases and a leading cause of chronic renal failure in women-of childbearing age. To evaluate the issue and possible complications of pregnancy in women with reflux nephropathy, we retrospectively analyzed fetal and maternal outcome in 158 women who had 375 pregnancies between 1965 and 1994. The overall fetal death rate was 10.2% and tended to decrease in the 1985 to 1994 decade as compared to the preceding period (8.4% vs. 12.6%). The relative risk of fetal death was 4.8 times greater hypertension was present at conception than in normotensive patients. Fetal death rate was also higher in patients with impaired renal function that in those with serum creatinine < 0.11 mmol/liter at conception (36.7% vs. 7.7%, P < 0.0001). Urinary tract infection accounted for frequent morbidity but seldom resulted in fetal mortality. Maternal renal disease was unaffected by pregnancy, excepted for 4 of the 21 patients with pre-existing renal failure who exhibited an irreversibly accelerated course after pregnancy. We conclude that pregnancy is essentially successful and uneventful in patients diagnosed with reflux nephropathy who have normal blood pressure and preserved renal function, whereas the fetal prognosis is more compromised and there is a risk of accelerated progression of maternal renal disease when serum creatinine concentration is in excess of 0.22 mmol/ liter. This suggests that women with reflux nephropathy should preferably conceive before having reached that stage of renal failure.

Alpha-Fetoprotein

Beginning in 1977, numerous studies have reported an association between high levels of maternal serum alpha-fetoprotein, measured in early pregnancy, and low birthweight and perinatal death. It has been suggested, however, that these findings may be explained by bias. We reviewed 21 studies and found that they were unanimous in reporting this association and that the association cannot be explained by any of the proposed biases. Comparing women whose alpha-fetoprotein levels were 2.5 times the median or more with all other women, the highest relative risk of fetal death was 21.0, with a 95% confidence interval of 8.4-52.2, and the lowest relative risk of fetal death was 4.4, with a 95% confidence interval of 2.8-7.0. For low birthweight (< 2,500 grams), the highest relative risk was 6.4 (95% confidence interval = 3.1-13.1) and the lowest relative risk was 1.9 (95% confidence interval = 1.5-2.5).

Alpha-Fetoprotein

Beginning in 1977, numerous studies have reported an association between high levels of maternal serum alpha-fetoprotein, measured in early pregnancy, and low birthweight and perinatal death. It has been suggested, however, that these findings may be explained by bias. We reviewed 21 studies and found that they were unanimous in reporting this association and that the association cannot be explained by any of the proposed biases. Comparing women whose alpha-fetoprotein levels were 2.5 times the median or more with all other women, the highest relative risk of fetal death was 21.0, with a 95% confidence interval of 8.4-52.2, and the lowest relative risk of fetal death was 4.4, with a 95% confidence interval of 2.8-7.0. For low birthweight (< 2,500 grams), the highest relative risk was 6.4 (95% confidence interval = 3.1-13.1) and the lowest relative risk was 1.9 (95% confidence interval = 1.5-2.5).

Risk factors associated with antepartum fetal death

This study examined risk factors that contribute to antepartum fetal death. The population-based sample included 416 antepartum fetal deaths and 449 normal births as controls, from 29 hospitals in Shanghai, China. In addition to small-forgestational-age and severe pregnancy-induced hypertension, exposure to environmental hazards (radiation, chemicals and pesticides) was significantly associated with fetal death. Elevated relative risk of fetal death was also found in pregnant women whose husbands smoked (adjusted odds ratio = 1.4). Clinico-pathologic evidence further confirmed that exposure to hazards, especially in the first trimester, increased the risks of congenital anomalies (odds ratio = 2.7) and antepartum fetal death from congenital malformations (odds ratio = 3.5). This study also showed that threatened abortion was a significant predictor of risk of fetal death. No significant relationships were identified between sex of fetus, mild or moderate pregnancy-induced hypertension, maternal anemia and antepartum fetal death.