Intrapartum cardiotocography with simultaneous maternal heart rate registration improves neonatal outcome.

BACKGROUND: Intrapartum cardiotocographic monitoring of fetal heart rate by abdominal external ultrasound transducer without simultaneous maternal heart rate recording has been associated with increased risk of early neonatal death and other asphyxia-related neonatal outcomes. It is unclear, however, whether this increase in risk is independently associated with fetal surveillance method or is attributable to other factors. OBJECTIVE: This study aimed to compare different fetal surveillance methods and their association with adverse short- and long-term fetal and neonatal outcomes in a large retrospective cohort of spontaneous term deliveries. STUDY DESIGN: Fetal heart rate and maternal heart rate patterns were recorded by cardiotocography during labor in spontaneous term singleton cephalic vaginal deliveries in the Hospital District of Helsinki and Uusimaa, Finland between October 1, 2005, and September 30, 2023. According to the method of cardiotocography monitoring at birth, the cohort was divided into the following 3 groups: women with ultrasound transducer, women with both ultrasound transducer and maternal heart rate transducer, and women with internal fetal scalp electrode. Umbilical artery pH and base excess values, low 1- and 5-minute Apgar scores, need for intubation and resuscitation, neonatal intensive care unit admission for asphyxia, neonatal encephalopathy, and early neonatal death were used as outcome variables. RESULTS: Among the 213,798 deliveries that met the inclusion criteria, the monitoring type was external ultrasound transducer in 81,559 (38.1%), both external ultrasound transducer and maternal heart rate recording in 62,268 (29.1%), and fetal scalp electrode in 69,971 (32.7%) cases, respectively. The rates of both neonatal encephalopathy (odds ratio, 1.48; 95% confidence interval, 1.08-2.02) and severe acidemia (umbilical artery pH <7.00 and/or umbilical artery base excess ≤-12.0 mmol/L) (odds ratio, 2.03; 95% confidence interval, 1.65-2.50) were higher in fetuses of women with ultrasound transducer alone compared with those of women with concurrent external fetal and maternal heart rate recording. Monitoring with ultrasound transducer alone was also associated with increased risk of neonatal intubation for resuscitation (odds ratio, 1.22; 95% confidence interval, 1.03-1.44). A greater risk of severe neonatal acidemia was observed both in the ultrasound transducer (odds ratio, 2.78; 95% confidence interval, 2.23-3.48) and concurrent ultrasound transducer and maternal heart rate recording (odds ratio, 1.37; 95% confidence interval, 1.05-1.78) groups compared with those monitored with fetal scalp electrodes. No difference in risk of neonatal encephalopathy was found between newborns monitored with concurrent ultrasound transducer and maternal heart rate recording and those monitored with fetal scalp electrodes. CONCLUSION: The use of external ultrasound transducer monitoring of fetal heart rate without simultaneous maternal heart rate recording is associated with higher rates of neonatal encephalopathy and severe neonatal acidemia. We suggest that either external fetal heart rate monitoring with concurrent maternal heart rate recording or internal fetal scalp electrode be used routinely as a fetal surveillance tool in term deliveries.

Is epidural analgesia non-inferior to intrathecal fentanyl as initiation for neuraxial analgesia in early non-spontaneous labour?

BACKGROUND AND AIM: Intrathecal fentanyl, using the combined spinal-epidural (CSE) technique, provides rapid analgesia during early labour. Because of the technique's more complex and invasive nature, as its replacement we assessed the use of epidural analgesia in primiparous parturients with induced labour. The study was registered at www. CLINICALTRIALS: gov (NCT04645823). The aim was to compare the efficacy, duration of analgesia and maternal satisfaction. The primary outcome was the difference in pain visual analogue scale (VAS) between the interventions at 20 min after the analgesia administration. METHODS: Sixty volunteering parturients were randomly allocated in 1:1 ratio to receive either intrathecal fentanyl 20 µg or epidural analgesia (fentanyl 100 µg and lidocaine 80 mg). Contraction pain and maternal satisfaction were assessed by 0-100 mm VAS for 30 min, respectively. Foetal heart rate abnormalities, the time to first epidural dose and the incidence of pruritus were recorded. Non-inferiority margin for mean (95% CI) VAS after epidural analgesia was set at 20 mm above the VAS value for intrathecal fentanyl at 20 min. RESULTS: The contraction pain VAS fell from (median [interquartile range, IQR]) 82 (14) to 13 (20) mm and 76 (17) to 12 (27) mm in 20 min following the intrathecal fentanyl and epidural analgesia, respectively. The absolute mean difference (epidural-intrathecal fentanyl) in the VAS values was 3.3(-0.06 to 6.66) mm indicating non-inferiority. The median time to reach VAS <30 mm was 10 min in both groups. The duration until request for supplemental analgesia was 82(69-95) and 91(75-106) min after intrathecal fentanyl and epidural analgesia, respectively. The difference for the duration (epidural-intrathecal fentanyl) was 9 (6-12) min and for satisfaction-VAS 0.3 (-3.0 to 3.7) mm. There were no differences between the groups in the incidence of foetal heart rate abnormalities, while pruritus was more common after intrathecal fentanyl. CONCLUSION: After 20 min, epidural analgesia by lidocaine and fentanyl was within the non-inferior threshold compared with intrathecal fentanyl in efficacy. The duration of action was not shorter than that of intrathecal fentanyl and maternal satisfaction was also similar.

Are labor epidural catheters after a combined spinal epidural (CSE) technique more reliable than after a traditional epidural? A retrospective review of 9153 labor epidural catheters.

BACKGROUND: The combined spinal epidural (CSE) technique may associate with a lower failure rate of epidural catheters compared to traditional epidural catheters. This may be significant for the parturients as failure of neuraxial analgesia has been associated with a negative impact on birth experience. METHODS: In this one-year retrospective study, the failure rate of epidural catheters was compared between 3201 and 5952 epidural catheters after initiation of neuraxial analgesia by the CSE or traditional epidural technique, respectively. Parturient background information, labor parameters, and neuraxial interventions were collected from 9153 parturients. Failure was defined as replacement of a used epidural catheter by new regional analgesia procedures or general anesthesia during intrapartum cesarean delivery. The primary outcome was the failure rate of epidural catheters. The secondary outcome was the time from the initial analgesia intervention to the epidural catheter replacement and progression of labor during this time. RESULTS: The CSE method was used at an earlier stage of labor, and the parturients were more often primiparous and undergoing induced labor. Earlier onset of analgesia, obesity, induced labor, anesthesiologist experience, and cesarean delivery were found to be significant cofactors for catheter failure. The unadjusted failure rate was 168/3201 (5.2%) and 223/5952 (3.7%) (OR 1.42 [1.16-1.75]) after initiation of analgesia by CSE or traditional epidural method. After controlling for the stage of labor, body mass index, induction of labor, and anesthesiologist's experience level, the adjusted OR for epidural catheter replacement was 1.04 (0.83-1.29) p = .736. The mean (SD) time until epidural catheter failure was 6.3 (4.4) and 4.0 (4.1) hours following initiation of analgesia by CSE or traditional epidural technique, respectively (p < .001). Cervical dilatation progressed from 4.3 (1.4) to 6.4 (2.1) cm and 5.1 (1.5) to 6.7 (1.7) cm between primary neuraxial analgesia and epidural catheter replacement. CONCLUSION: CSE technique was not associated with a better survival rate of epidural catheters for provision of analgesia or epidural top-up anesthesia for intrapartum CD. In addition, the time to replacement of the catheter was significantly longer when analgesia was initiated with the CSE technique. Maternal satisfaction scores were lower if catheters required replacement.

Multifetal pregnancy reductions and selective fetocide in a tertiary referral center - a retrospective cohort study.

OBJECTIVES: Multiple pregnancies involve several complications, most often prematurity, but also higher anomaly rates. Reducing fetuses generally improves pregnancy outcomes. We conducted this study to evaluate the obstetrical and neonatal results after multifetal pregnancy reduction (MFPR) in the largest tertiary hospital in Finland. METHODS: This retrospective cohort study included all MFPR managed in Helsinki University Hospital during a 13 year period (2007-2019). Data on pregnancies, parturients and newborns were collected from patient files. The number of fetuses, chorionicities and amnionicities were defined in first-trimester ultrasound screening. RESULTS: There were 54 MFPR cases included in the final analyses. Most often the reduction was from twins to singletons (n=34, 63 %). Majority of these (25/34, 73.5 %) were due to co-twin anomaly. Triplets (n=16, 29.6 %) were reduced to twins (n=7, 13 %) or singletons (n=9, 16.7 %), quadruplets (n=2, 3.7 %) and quintuplets (n=2, 3.7 %) to twins. Most (33/54, 61.1 %) MFPR procedures were done by 15+0 weeks of gestation. There were six miscarriages after MFPR and one early co-twin miscarriage. In the remaining 47 pregnancies that continued as twins (n=7, 14.9 %) or singletons (n=40, 85.1 %) the liveborn rate was 90 % for one fetus and 71.4 % for two fetuses. CONCLUSIONS: Most MFPR cases were pregnancies with an anomalous co-twin. The whole pregnancy loss risk was 11.1 % after MFPR. The majority (70.6 %) of twins were spontaneous, whereas all quadruplets, quintuplets, and 56.3 % of triplets were assisted reproductive technologies (ART) pregnancies. Careful counselling should be an essential part of obstetrical care in multiple pregnancies, which should be referred to fetomaternal units for MFPR option.

The outcome of reduced and non-reduced triplet pregnancies managed in a tertiary hospital during a 15-year-period - a retrospective cohort study.

OBJECTIVES: Triplet pregnancies involve several complications, the most important being prematurity as virtually all triplets are born preterm. We conducted this study to compare the outcomes of reduced vs. non-reduced triplet pregnancies managed in the largest tertiary hospital in Finland. METHODS: This was a retrospective cohort study in the Helsinki University Hospital during 2006-2020. Data on the pregnancies, parturients and newborns were collected from patient records. The fetal number, chorionicity and amnionicity were defined in first-trimester ultrasound screening. The main outcome measures were perinatal and neonatal mortality of non-reduced triplets, compared to twins and singletons selectively reduced of triplet pregnancies. RESULTS: There were 57 initially triplet pregnancies and 35 of these continued as non-reduced triplets and resulted in the delivery of 104 liveborn children. The remaining 22 cases were spontaneously or medically reduced to twins (9) or singletons (13). Most (54.4 %) triplet pregnancies were spontaneous. There were no significant differences in gestational age at delivery between triplets (mean 33+0, median 34+0) and those reduced to twins (mean 32+5, median 36+0). The survival at one week of age was higher for triplets compared to twins (p<0.00001). CONCLUSIONS: Most pregnancies continued as non-reduced triplets, which were born at a similar gestational age but with a significantly higher liveborn rate compared to those reduced to twins. There were no early neonatal deaths among cases reduced to singletons. Prematurity was the greatest concern for multiples in this cohort, whereas the small numbers may explain the lack of difference in gestational age between these groups.

Perinatal outcome of dichorionic and monochorionic-diamniotic Finnish twins: a historical cohort study.

INTRODUCTION: Although the perinatal mortality of monochorionic twins has been reported to be higher, the role of chorionicity is debated and data from Finland are still lacking. To examine the effect of chorionicity on the main outcome measures, perinatal and neonatal mortality and neonatal morbidity of Finnish twins, a comprehensive population-based historical cohort study was performed at Helsinki University Hospitals. MATERIAL AND METHODS: All 1034 dichorionic and monochorionic-diamniotic twin pregnancies managed at Helsinki University Hospital area during 2006, 2010, 2014 and 2018 were collected from patient databases. Information on chorionicity was retrieved from ultrasound reports and all relevant clinical information from patient records. Differences in perinatal and neonatal mortality and neonatal morbidity were analyzed by performing group comparisons between the twins and chorionicity. The role of chorionicity was also assessed in logistic regression analyses. RESULTS: There were 1034 dichorionic-diamniotic (DCDA, n = 789, 76.3%, 95% confidence interval [CI] 73.6-78.9) and monochorionic-diamniotic (MCDA, n = 245, 23.7%, 95% CI 21.4-26.0) twin pregnancies during the studied years. Most (n = 580, 56.1%, 95% CI 52.8-59.2) twins were born at term, but 151 (61.6%, 95% CI 55.8-67.3) of MCDA twins were preterm and had lower birthweight and Apgar scores and higher risk of death of one twin. Perinatal and neonatal mortality did not differ between twins A and B, but the immediate outcome of twin B was worse, with lower arterial pH and Apgar scores and increased need of neonatal intensive care unit treatment. CONCLUSIONS: Chorionicity contributes to the perinatal and neonatal outcome in favor of dichorionic twins. This disadvantage of MCDA twinning is likely explained by earlier gestational age at birth and inequal placental sharing. Irrespective of chorionicity, twin B faces more complications.

Excellent perinatal outcome of monoamniotic twin pregnancy with timely diagnosis and optimal management - a retrospective cohort study.

OBJECTIVES: Monoamniotic twins represent a high-risk pregnancy requiring intense follow-up, elective birth and careful consideration of the mode and timing of delivery. We conducted this study to evaluate the perinatal and neonatal outcomes of monoamniotic twin pregnancies in the largest tertiary hospital in Finland. METHODS: This was a retrospective cohort study including all monoamniotic twin pregnancies during a 17-year period (2002-2018) managed in Helsinki University Hospital. Data on mothers and children were collected from patient files. Chorionicity and amnionicity were defined in first-trimester ultrasound screening. RESULTS: There were altogether 31 monoamniotic twin pregnancies during the study period, including four cases of conjoined twins which all underwent termination of pregnancy, and three miscarriages. In the remaining 24 pregnancies that continued past 24 weeks of gestation there was 97.9% survival (one intrauterine death). Three pregnancies were complicated with twin-to-twin transfusion syndrome. All children were delivered by cesarean section with a mean gestational age of 32 + 5 weeks (27 + 1-34 + 2 weeks). Respiratory distress syndrome (RDS) was observed in 57% (27/47) of neonates and grade I-II intraventricular haemorrhage (IVH) in 6.3% (3/47) of neonates. There were no neonatal deaths and no maternal complications. CONCLUSIONS: Monoamniotic twinning is a rare form of pregnancy and carries risks for perinatal and neonatal complications. With timely diagnosis, close monitoring in specialized feto-maternal unit and elective delivery at 32-34 weeks the outcome is usually excellent.

Time points and risk factors for RhD immunizations after the implementation of targeted routine antenatal anti-D prophylaxis: A retrospective nationwide cohort study.

INTRODUCTION: Targeted routine antenatal anti-D prophylaxis was introduced to the national prophylaxis program in Finland in late 2013. The aim of this study was to assess the incidence, time-points, and risk factors for Rhesus D immunization after the implementation of routine antenatal anti-D prophylaxis, in all women in Finland with antenatal anti-D antibodies detected in 2014-2017. MATERIAL AND METHODS: In a nationwide population-based retrospective cohort study, the incidence, time-points, and risk factors of anti-D immunizations were analyzed. Information on antenatal screening was obtained from the Finnish Red Cross Blood Service database, and obstetric data from hospital records and the Finnish Medical Birth Register. RESULTS: The study included a total of 228 women (197 with complete data for all pregnancies). After the implementation of routine antenatal anti-D prophylaxis, the prevalence of pregnancies with anti-D antibodies decreased from 1.52% in 2014 to 0.88% in 2017, and the corresponding incidence of new immunizations decreased from 0.33% to 0.10%. Time-points for detection of new anti-D antibodies before and after 2014 were the first screening sample at 8-12 weeks of gestation in 52% vs 19%, the second sample at 24-26 weeks in 20% vs 50%, and the third screening at 36 weeks in 28% vs 32%. CONCLUSIONS: The incidence of new anti-D immunizations decreased as expected after the implementation of routine antenatal anti-D prophylaxis. True failures are rare and they mainly occur when the prophylaxis is not given appropriately, suggesting a need for constant education of healthcare professionals on the subject.

Correction to: Maternal complications in twin pregnancies in Finland during 1987-2014: a retrospective study.

An amendment to this paper has been published and can be accessed via the original article.

Correction to: Perinatal outcomes in Finnish twins: a retrospective study.

An amendment to this paper has been published and can be accessed via the original article.

Perinatal outcomes in Finnish twins: a retrospective study.

BACKGROUND: To establish the changes in perinatal morbidity and mortality in twin pregnancies in Finland, a retrospective register research was conducted. Our extensive data from a 28-year study period provide important information on the outcome of twin pregnancies in Finland that has previously not been reported to this extent. METHODS: All 23,498 twin pregnancies with 46,996 children born in Finland during 1987-2014 were included in the study. Data were gathered from the Medical Birth Register and the Hospital Discharge Register (Finnish Institute for Health and Welfare, Finland) regarding perinatal mortality (PNM) and morbidity. For statistical analysis, binomial regression analysis and crosstabs were performed. The results are expressed in means, percentages and ranges with comparison to singletons when appropriate. Odds ratios from binomial regression analysis are reported. A p-value <0.05 was considered statistically significant. RESULTS: There were 46,363 liveborn and 633 stillborn twins in Finland during 1987-2014. Perinatal mortality decreased markedly, from 45.1 to 6.5 per 1000 for twin A and from 54.1 to 11.9 per 1000 for twin B during the study period. Yet, the PNM difference between twin A and B remained. Early neonatal mortality did not differ between twins, but has decreased in both. Asphyxia, respiratory distress syndrome, need for antibiotics and Neonatal Intensive Care Unit (NICU) stay were markedly more common in twin B. CONCLUSIONS: In Finland, PNM and early neonatal mortality in twins decreased significantly during 1987-2014 and are nowadays very low. However, twin B still faces more complications. The outline provided may be used to further improve the monitoring and thus perinatal outcome of twins, especially twin B.

Maternal complications in twin pregnancies in Finland during 1987-2014: a retrospective study.

BACKGROUND: To investigate the trends and changes in the incidence and overall outcome of twin pregnancies in Finland, a retrospective study was conducted with emphasis on maternal complications, covering a 28-year study period. METHODS: All 23,498 twin pregnancies with 46,363 live born and 633 stillborn children in Finland during 1987-2014 were included in the study. Data were collected from the national Medical Birth Register and the Care Register on Hospital Care (Finnish Institute for Health and Welfare, Finland) regarding the parturients' characteristics and incidences of several pregnancy and childbirth complications. The incidences of twin pregnancies and maternal complications during pregnancy and childbirth are the main outcome measures of the study. The results are expressed in percentages, means, medians, ranges and standard deviations (SD), when appropriate. RESULTS: Twins comprised 1.4% of all births in Finland in 1987-2014. Parturients' mean age has remained stable, but the share of over 35 year-old parturients is increasing. The incidences of pre-eclampsia, intrahepatic cholestasis of pregnancy, gestational diabetes and postpartum haemorrhage have risen during the study period. Almost half (44.9%) of twins were born preterm, almost half via Caesarean section (47.1%), and 27.7% of twin labours were induced. CONCLUSIONS: Several pregnancy complications increased during the study period. Advanced maternal age among twin parturients has risen, enhancing the risks for developing complications in a pregnancy already of a high-risk category, and predisposing to preterm delivery. National and international guidelines are necessary to improve the overall outcome of twin pregnancies.

Case report: Severe hemolytic disease of the fetus and newborn due to anti-C+G.

Anti-G is commonly present with anti-D and/or anti-C and can confuse serological investigations. in general, anti-G is not considered a likely cause of severe hemolytic disease of the fetus and newborn (HDFN), but it is important to differentiate it from anti-D in women who should be administered anti-D immunoglobulin prophylaxis. We report one woman with three pregnancies severely affected by anti-C+G requiring intrauterine treatment and a review of the literature. In our case, the identification of the correct antibody was delayed because the differentiation of anti-C+G and anti-D+C was not considered important during pregnancy since the father was D-. In addition, anti-C+G and anti-G titer levels were not found to be reliable as is generally considered in Rh immunization. Severe HDFN occurred at a maternal anti-C+G antibody titer of S and anti-G titer of 1 in comparison with the critical titer level of 16 or more in our laboratory. close collaboration between the immunohematology laboratory and the obstetric unit is essential. In previously affected families, early assessment for fetal anemia is required even when titers are low.

[Sleep-related breathing disorders in pregnancy--a predictor of pre-eclampsia?]. / Unenaikaiset hengityshäiriöt raskauden aikana--pre-eklampsian enne?

Sleep disorders are common in pregnancy. Several hormonal and physiological changes have been shown to affect the quality of sleep. Sleep disorders have been related to various pregnancy complications, e.g. pre-eclampsia. In particular, sleep apnea is more common among women who develop hypertension in pregnancy or pre-eclampsia. Compared with control patients, snoring is similarly more often apparent in women who will have pre-eclampsia manifested. Hence, the relationship between sleep disorders and pre-eclampsia warrants investigation. CPAP treatment has been proven to be effective in sleep apnea, but also in lowering blood pressure. CPAP may be useful also in the prevention and treatment of pre-eclampsia.

Mode of delivery of Finnish dichorionic and monochorionic-diamniotic twins: A retrospective observational study including a risk score for intrapartum cesarean birth.

Background and Aims: Trial of labor is considered safe also among twins, yet nearly 50% are born via cesarean section in Finland. While planned cesarean births have declined among twins, intrapartum cesarean deliveries have risen, postulating evaluation of criteria for trial of labor. The objective of this study was to create an outline of the mode of delivery of dichorionic and monochorionic-diamniotic Finnish twins. By evaluating risk factors for intrapartum cesarean delivery (CD), we aimed at creating a risk score for intrapartum cesarean birth for twins. Methods: A retrospective observational study based on a cohort of dichorionic and monochorionic-diamniotic twin pregnancies considered as candidates for trial of labor in 2006, 2010, 2014, and 2018 (n = 720) was performed. Differences between parturients with vaginal delivery and intrapartum CD to identify potential risk factors for intrapartum CD were assessed. Logistic regression analysis (n = 707) was used to further define risk score points for recognized risk factors. Results: A total of 23.8% (171/720, 95% confidence interval [CI] = 20.7-26.9) of parturients experienced intrapartum CD. Induction of labor, primiparity, fear of childbirth, artificial reproductive technology, higher maternal age, and other than cephalic/cephalic presentation independently associated with intrapartum CD. The achieved total risk score ranged from 0 to 13 points with significantly higher points among the CD group (6.61 vs. 4.42, p < 0.001). Using ≥8 points as a cut-off, 51.4% (56/109) were delivered by intrapartum CD (sensitivity = 33.73%, specificity = 90.20%, positive predictive value = 51.38%, negative predictive value = 81.61%). The total risk score had a fair predictive capability for intrapartum CD (area under the curve = 0.729, 95% CI = 0.685-0.773). Conclusion: Fair-level risk stratification could be achieved with higher maternal age, primiparity, induction of labor, artificial reproductive technology, fear of childbirth, and other than cephalic/cephalic presentation increasing the risk. Parturients with low-risk score (0-7 points) appear to be the best candidates for trial of labor with acceptable CD rates in this group (18.4%).

Successful pregnancy and cesarean delivery in a tetraplegic, home-invasively-mechanically-ventilated patient - case report.

INTRODUCTION: Pregnancies are rare in patients with severely disabilitating spinal cord injuries (SCI) but increasing alongside social awareness concerning reproductive equality. Physicians should be aware of several potential complications during pregnancy and delivery, particularly autonomic dysreflexia. CASE PRESENTATION: We report a successful pregnancy of a 32-year-old woman with a severe SCI at the C2 level (C1-4 ASIA Impairment Scale grade A) and total dependency on home invasive mechanical ventilation (HIMV), an extremely rare treatment. An elective cesarean section was chosen as the delivery mode at 34 + 0 weeks of gestation. Both the mother and the child recovered well. DISCUSSION: Severe spinal cord injury and dependency on mechanical ventilation are not absolute contraindications for pregnancy. With careful planning, pregnancy is possible also for patients with the most severe forms of SCI. Adequate pain relief during cesarean delivery is required despite complete spinal cord injury in order to avoid excessive hemodynamic responses and spinal reflexes. A multidisciplinary team is needed to ensure safe pregnancy and delivery of these high-risk pregnancies.

Upper-airway flow limitation and transcutaneous carbon dioxide during sleep in normal pregnancy.

OBJECTIVE: Sleep during pregnancy involves a physiological challenge to provide sufficient gas exchange to the fetus. Enhanced ventilatory responses to hypercapnia and hypoxia may protect from deficient gas exchange, but sleep-disordered breathing (SDB) may predispose to adverse events. The aim of this study was to analyze sleep and breathing in healthy pregnant women compared to non-pregnant controls, with a focus on CO2 changes and upper-airway flow limitation. METHODS: Healthy women in the third trimester and healthy non-pregnant women with normal body mass index (BMI) were recruited for polysomnography. Conventional analysis of sleep and breathing was performed. Transcutaneous carbon dioxide (TcCO2) was determined for each sleep stage. Flow-limitation was analyzed using the flattening index and TcCO2 values were recorded for every inspiration. RESULTS: Eighteen pregnant women and 12 controls were studied. Pregnancy was associated with shorter sleep duration and more superficial sleep. Apnea-hypopnea index, arterial oxyhemoglobin desaturation, flow-limitation, snoring or periodic leg movements were similar in the two groups. Mean SaO2 and minimum SaO2 were lower and average heart rate was higher in the pregnant group. TcCO2 levels did not differ between groups but variance of TcCO2 was smaller in pregnant women during non-rapid eye movement (NREM). TcCO2 profiles showed transient TcCO2 peaks, which seem specific to pregnancy. CONCLUSIONS: Healthy pregnancy does not predispose to SDB. Enhanced ventilatory control manifests as narrowing threshold of TcCO2 between wakefulness and sleep. Pregnant women have a tendency for rapid CO2 increases during sleep which might have harmful consequences if not properly compensated.