Gunther Ruyssinck - Academia.edu (original) (raw)

Papers by Gunther Ruyssinck

Research paper thumbnail of Perinatal outcome of ICSI pregnancies compared with a matched group of natural conception pregnancies in Flanders (Belgium)

A retrospective cohort study was conducted with an intracytoplasmic sperm injection (ICSI) group ... more A retrospective cohort study was conducted with an intracytoplasmic sperm injection (ICSI) group and a naturally conceived comparison group. A total of 1655 singleton and 1102 twin ICSI births were studied with regard to perinatal outcome. Control subjects (naturally conceived pregnancies) were selected from a regional registry and were matched for maternal age, parity, place of delivery, year of birth and fetal sex. The main outcome measures were duration of pregnancy, birth weight, Apgar score <5 after 5 min, neonatal complications, perinatal death and congenital malformations. Twin births, when compared with singletons, carry a much higher risk of poor perinatal outcome. For both ICSI singletons and ICSI twins, no significant difference was found between ICSI and naturally conceived pregnancies for all investigated parameters. After excluding likesex twin pairs, ICSI twin pregnancies were at increased risk for perinatal mortality (OR = 2.74, CI = 1.26-5.98), prematurity (OR = 1.38, CI = 1.10-1.75) and low birth weight (OR = 1.34, CI = 1.06-1.69) compared with spontaneously conceived different-sex twin pairs. In conclusion, the perinatal outcome of ICSI singleton and twin pregnancies was very similar to that of spontaneously conceived pregnancies in this large cohort study. After excluding like-sex twin pairs, ICSI twins were at increased risk for prematurity, low birth weight and higher perinatal mortality compared with the natural conception comparison group.

Research paper thumbnail of A Matched Cohort Comparison of the Outcome of Twin Versus Singleton Pregnancies in Flanders, Belgium

Twin Research, 2003

were compared to singletons, matched for gestational age, fetal sex and maternal parity, resultin... more were compared to singletons, matched for gestational age, fetal sex and maternal parity, resulting in 4384 infants in each group. Above 32 weeks of gestation, birthweight was significantly lower in twins (2095 ± 364 g versus 2315 ± 523 g; p < 0.001, 95% confidence interval 193 to 246 g). Perinatal mortality was also significantly lower in twins (1.98% versus 1.26%; odds ratio for twins 0.63; 95% confidence interval 0.53-0.75; p < 0.001 ), this was mostly due to fetal and not to early neonatal mortality. Congenital malformations occurred less frequently in twins (2.5% versus 3.7%; odds ratio for twins 0.80, 95% confidence interval 0.69-0.92; p = 0.001). From gestational age of 32 weeks on, respiratory distress syndrome was less frequent in twins (6.7% versus 8.0%; odds ratio for twins 0.81; 95% confidence interval 0.68-0.97; p = 0.011 ). No significant differences were noted with regard to intraventricular haemorrhage, neonatal infections and retinopathy of prematurity. Although twins have a lower birthweight, their outcome is more favorable compared to singletons, when matched for gestational age.

Research paper thumbnail of A Matched Cohort Comparison of the Outcome of Twin Versus Singleton Pregnancies in Flanders, Belgium

Twin Research, 2003

were compared to singletons, matched for gestational age, fetal sex and maternal parity, resultin... more were compared to singletons, matched for gestational age, fetal sex and maternal parity, resulting in 4384 infants in each group. Above 32 weeks of gestation, birthweight was significantly lower in twins (2095 ± 364 g versus 2315 ± 523 g; p < 0.001, 95% confidence interval 193 to 246 g). Perinatal mortality was also significantly lower in twins (1.98% versus 1.26%; odds ratio for twins 0.63; 95% confidence interval 0.53-0.75; p < 0.001 ), this was mostly due to fetal and not to early neonatal mortality. Congenital malformations occurred less frequently in twins (2.5% versus 3.7%; odds ratio for twins 0.80, 95% confidence interval 0.69-0.92; p = 0.001). From gestational age of 32 weeks on, respiratory distress syndrome was less frequent in twins (6.7% versus 8.0%; odds ratio for twins 0.81; 95% confidence interval 0.68-0.97; p = 0.011 ). No significant differences were noted with regard to intraventricular haemorrhage, neonatal infections and retinopathy of prematurity. Although twins have a lower birthweight, their outcome is more favorable compared to singletons, when matched for gestational age.

Research paper thumbnail of Perinatal outcome of ICSI pregnancies compared with a matched group of natural conception pregnancies in Flanders (Belgium): a cohort study

Reproductive BioMedicine Online, 2005

A retrospective cohort study was conducted with an intracytoplasmic sperm injection (ICSI) group ... more A retrospective cohort study was conducted with an intracytoplasmic sperm injection (ICSI) group and a naturally conceived comparison group. A total of 1655 singleton and 1102 twin ICSI births were studied with regard to perinatal outcome. Control subjects (naturally conceived pregnancies) were selected from a regional registry and were matched for maternal age, parity, place of delivery, year of birth and fetal sex. The main outcome measures were duration of pregnancy, birth weight, Apgar score <5 after 5 min, neonatal complications, perinatal death and congenital malformations. Twin births, when compared with singletons, carry a much higher risk of poor perinatal outcome. For both ICSI singletons and ICSI twins, no significant difference was found between ICSI and naturally conceived pregnancies for all investigated parameters. After excluding likesex twin pairs, ICSI twin pregnancies were at increased risk for perinatal mortality (OR = 2.74, CI = 1.26-5.98), prematurity (OR = 1.38, CI = 1.10-1.75) and low birth weight (OR = 1.34, CI = 1.06-1.69) compared with spontaneously conceived different-sex twin pairs. In conclusion, the perinatal outcome of ICSI singleton and twin pregnancies was very similar to that of spontaneously conceived pregnancies in this large cohort study. After excluding like-sex twin pairs, ICSI twins were at increased risk for prematurity, low birth weight and higher perinatal mortality compared with the natural conception comparison group.

Research paper thumbnail of Obstetric and perinatal outcome of 1655 ICSI and 3974 IVF singleton and 1102 ICSI and 2901 IVF twin births: a comparative analysis

Reproductive BioMedicine Online, 2005

A total of 3974 IVF and 1655 ICSI singleton births and 2901 IVF and 1102 ICSI twin births were ev... more A total of 3974 IVF and 1655 ICSI singleton births and 2901 IVF and 1102 ICSI twin births were evaluated. Pregnancies after both fresh and frozen transfers were included. IVF and ICSI singleton pregnancies were very similar for most obstetric and perinatal variables. The only significant difference was a higher risk for prematurity (<37 weeks of amenorrhoea) in IVF pregnancies compared with ICSI pregnancies (12.4 versus 9.2%, OR = 1.39, 95% CI = 1.15-1.70). For twin pregnancies, differences were not statistically different except for a higher incidence of stillbirths in the ICSI group (2.08 versus 1.03%, OR = 2.04, 95% CI = 1.14-3.64). Intrauterine growth retardation with or without pregnancy-induced hypertension was observed more often in the ICSI group. Regression analysis of the data with correction for parity and female age showed similar results for twins. For singletons, this analysis showed similar results with the exception of low birth weight babies (<2500 g), which were also observed more often in IVF pregnancies (9.6 versus 7.9%, OR = 0.79, CI = 0.65-0.98, P = 0.03). This large case-comparative retrospective analysis showed that the obstetric outcome and perinatal health of IVF and ICSI pregnancies is comparable.

Research paper thumbnail of Outcome after elective labor induction in nulliparous women: A matched cohort study

American Journal of Obstetrics and Gynecology, 2002

To determine whether elective induction of labor in nulliparous women is associated with changes ... more To determine whether elective induction of labor in nulliparous women is associated with changes in fetomaternal outcome when compared with labor of spontaneous onset. All 80 labor wards in Flanders (Northern Belgium) comprised a matched cohort study. From 1996 through 1997, 7683 women with elective induced labor and 7683 women with spontaneous labor were selected according to the following criteria: nulliparity, singleton pregnancy, cephalic presentation, gestational age at the time of delivery of 266 to 287 days, and birth weight between 3000 and 4000 g. Each woman with induced labor and the corresponding woman with spontaneous labor came from the same labor ward, and they had babies of the same sex. Both groups were compared with respect to the incidence of cesarean delivery or instrument delivery and the incidence of transfer to the neonatal ward. Cesarean delivery (9.9% vs 6.5%), instrumental delivery (31.6% vs 29.1%), epidural analgesia (80% vs 58%), and transfer of the baby to the neonatal ward (10.7% vs 9.4%) were significantly more common (P &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;.01) when labor was induced electively. The difference in cesarean delivery was due to significantly more first-stage dystocia in the induced group. The difference in neonatal admission could be attributed to a higher admission rate for maternal convenience when the women had a cesarean delivery. When compared with labor of spontaneous onset, elective labor induction in nulliparous women is associated with significantly more operative deliveries. Nulliparous women should be informed about this before they submit to elective induction.

Research paper thumbnail of Perinatal outcome of pregnancies after assisted reproduction: A case-control study

American Journal of Obstetrics and Gynecology, 1999

We conducted a case-control study of all pregnancies obtained with assisted reproduction technolo... more We conducted a case-control study of all pregnancies obtained with assisted reproduction technology in the Dutch-speaking part of Belgium from 1992 until 1997 to investigate differences in peripartum obstetric events and the perinatal outcome. Three thousand fifty-seven singleton and 1241 twin pregnancies were studied. About 90% of pregnancies resulted from in vitro fertilization; the remainder resulted from intracytoplasmic sperm injection. Control subjects were selected from a regional register and were matched for maternal age, parity, fetal sex, plurality, and date of delivery. The main outcome measures were duration of gestation, birth weight, perinatal death, perinatal morbidity, incidence of congenital malformations, and incidence of cesarean delivery. Odds ratios and 95% confidence intervals were 2.6 (1.4-4.8) for perinatal mortality, 3.5 (2.2-5.7) for birth before 33 weeks of gestation, and 1.7 (1.5-1.9) for cesarean delivery in singleton pregnancies that resulted after in vitro fertilization. Twin pregnancies obtained with in vitro fertilization, on the contrary, were similar for all outcome measures, except for the incidence of cesarean delivery (odds ratio, 1.4; 95% confidence interval, 1.2-1.7) compared with spontaneously conceived twin pregnancies. The perinatal outcome of singleton pregnancies obtained with in vitro fertilization is significantly worse than that of spontaneously conceived pregnancies, mainly because of the increased rate of preterm birth. The outcome of twin pregnancies obtained with in vitro fertilization is comparable with that of normally conceived twins. For both singleton and twin pregnancies obtained with in vitro fertilization, the incidence of cesarean delivery is increased.

Research paper thumbnail of Perinatal outcome of 12 021 singleton and 3108 twin births after non-IVF-assisted reproduction: a cohort study

Human Reproduction, 2005

Perinatal outcome of pregnancies caused by assisted reproduction technique (ART) is substantially... more Perinatal outcome of pregnancies caused by assisted reproduction technique (ART) is substantially worse when compared with pregnancies following natural conception. We investigated the possible risks of non-IVF ART on perinatal health. We conducted a retrospective cohort study with two exposure groups: a study group of pregnancies after controlled ovarian stimulation (COS), with or without artificial insemination (AI), and a naturally conceived comparison group. We used the data from the regional registry of all hospital deliveries in the Dutch-speaking part of Belgium during the period from January 1993 until December 2003 to investigate differences in perinatal outcome of singleton and twin pregnancies. 12 021 singleton and 3108 twin births could be selected. Naturally conceived subjects were matched for maternal age, parity, fetal sex and year of birth. The main outcome measures were duration of pregnancy, birth weight, perinatal morbidity and perinatal mortality. Our overall results showed a significantly higher incidence of prematurity (<32 and <37 weeks), low and very low birth weight, transfer to the neonatal intensive care unit and most neonatal morbidity parameters for COS/AI singletons. Twin pregnancies resulting from COS/AI showed an increased rate of neonatal mortality, assisted ventilation and respiratory distress syndrome. After excluding same-sex twin sets, COS/AI twin pregnancies were at increased risk for extreme prematurity and very low birth weight. In conclusion, COS/AI singleton and twin pregnancies are significantly disadvantaged compared to naturally conceived children.

Research paper thumbnail of Perinatal outcome of ICSI pregnancies compared with a matched group of natural conception pregnancies in Flanders (Belgium)

A retrospective cohort study was conducted with an intracytoplasmic sperm injection (ICSI) group ... more A retrospective cohort study was conducted with an intracytoplasmic sperm injection (ICSI) group and a naturally conceived comparison group. A total of 1655 singleton and 1102 twin ICSI births were studied with regard to perinatal outcome. Control subjects (naturally conceived pregnancies) were selected from a regional registry and were matched for maternal age, parity, place of delivery, year of birth and fetal sex. The main outcome measures were duration of pregnancy, birth weight, Apgar score <5 after 5 min, neonatal complications, perinatal death and congenital malformations. Twin births, when compared with singletons, carry a much higher risk of poor perinatal outcome. For both ICSI singletons and ICSI twins, no significant difference was found between ICSI and naturally conceived pregnancies for all investigated parameters. After excluding likesex twin pairs, ICSI twin pregnancies were at increased risk for perinatal mortality (OR = 2.74, CI = 1.26-5.98), prematurity (OR = 1.38, CI = 1.10-1.75) and low birth weight (OR = 1.34, CI = 1.06-1.69) compared with spontaneously conceived different-sex twin pairs. In conclusion, the perinatal outcome of ICSI singleton and twin pregnancies was very similar to that of spontaneously conceived pregnancies in this large cohort study. After excluding like-sex twin pairs, ICSI twins were at increased risk for prematurity, low birth weight and higher perinatal mortality compared with the natural conception comparison group.

Research paper thumbnail of A Matched Cohort Comparison of the Outcome of Twin Versus Singleton Pregnancies in Flanders, Belgium

Twin Research, 2003

were compared to singletons, matched for gestational age, fetal sex and maternal parity, resultin... more were compared to singletons, matched for gestational age, fetal sex and maternal parity, resulting in 4384 infants in each group. Above 32 weeks of gestation, birthweight was significantly lower in twins (2095 ± 364 g versus 2315 ± 523 g; p < 0.001, 95% confidence interval 193 to 246 g). Perinatal mortality was also significantly lower in twins (1.98% versus 1.26%; odds ratio for twins 0.63; 95% confidence interval 0.53-0.75; p < 0.001 ), this was mostly due to fetal and not to early neonatal mortality. Congenital malformations occurred less frequently in twins (2.5% versus 3.7%; odds ratio for twins 0.80, 95% confidence interval 0.69-0.92; p = 0.001). From gestational age of 32 weeks on, respiratory distress syndrome was less frequent in twins (6.7% versus 8.0%; odds ratio for twins 0.81; 95% confidence interval 0.68-0.97; p = 0.011 ). No significant differences were noted with regard to intraventricular haemorrhage, neonatal infections and retinopathy of prematurity. Although twins have a lower birthweight, their outcome is more favorable compared to singletons, when matched for gestational age.

Research paper thumbnail of A Matched Cohort Comparison of the Outcome of Twin Versus Singleton Pregnancies in Flanders, Belgium

Twin Research, 2003

were compared to singletons, matched for gestational age, fetal sex and maternal parity, resultin... more were compared to singletons, matched for gestational age, fetal sex and maternal parity, resulting in 4384 infants in each group. Above 32 weeks of gestation, birthweight was significantly lower in twins (2095 ± 364 g versus 2315 ± 523 g; p < 0.001, 95% confidence interval 193 to 246 g). Perinatal mortality was also significantly lower in twins (1.98% versus 1.26%; odds ratio for twins 0.63; 95% confidence interval 0.53-0.75; p < 0.001 ), this was mostly due to fetal and not to early neonatal mortality. Congenital malformations occurred less frequently in twins (2.5% versus 3.7%; odds ratio for twins 0.80, 95% confidence interval 0.69-0.92; p = 0.001). From gestational age of 32 weeks on, respiratory distress syndrome was less frequent in twins (6.7% versus 8.0%; odds ratio for twins 0.81; 95% confidence interval 0.68-0.97; p = 0.011 ). No significant differences were noted with regard to intraventricular haemorrhage, neonatal infections and retinopathy of prematurity. Although twins have a lower birthweight, their outcome is more favorable compared to singletons, when matched for gestational age.

Research paper thumbnail of Perinatal outcome of ICSI pregnancies compared with a matched group of natural conception pregnancies in Flanders (Belgium): a cohort study

Reproductive BioMedicine Online, 2005

A retrospective cohort study was conducted with an intracytoplasmic sperm injection (ICSI) group ... more A retrospective cohort study was conducted with an intracytoplasmic sperm injection (ICSI) group and a naturally conceived comparison group. A total of 1655 singleton and 1102 twin ICSI births were studied with regard to perinatal outcome. Control subjects (naturally conceived pregnancies) were selected from a regional registry and were matched for maternal age, parity, place of delivery, year of birth and fetal sex. The main outcome measures were duration of pregnancy, birth weight, Apgar score <5 after 5 min, neonatal complications, perinatal death and congenital malformations. Twin births, when compared with singletons, carry a much higher risk of poor perinatal outcome. For both ICSI singletons and ICSI twins, no significant difference was found between ICSI and naturally conceived pregnancies for all investigated parameters. After excluding likesex twin pairs, ICSI twin pregnancies were at increased risk for perinatal mortality (OR = 2.74, CI = 1.26-5.98), prematurity (OR = 1.38, CI = 1.10-1.75) and low birth weight (OR = 1.34, CI = 1.06-1.69) compared with spontaneously conceived different-sex twin pairs. In conclusion, the perinatal outcome of ICSI singleton and twin pregnancies was very similar to that of spontaneously conceived pregnancies in this large cohort study. After excluding like-sex twin pairs, ICSI twins were at increased risk for prematurity, low birth weight and higher perinatal mortality compared with the natural conception comparison group.

Research paper thumbnail of Obstetric and perinatal outcome of 1655 ICSI and 3974 IVF singleton and 1102 ICSI and 2901 IVF twin births: a comparative analysis

Reproductive BioMedicine Online, 2005

A total of 3974 IVF and 1655 ICSI singleton births and 2901 IVF and 1102 ICSI twin births were ev... more A total of 3974 IVF and 1655 ICSI singleton births and 2901 IVF and 1102 ICSI twin births were evaluated. Pregnancies after both fresh and frozen transfers were included. IVF and ICSI singleton pregnancies were very similar for most obstetric and perinatal variables. The only significant difference was a higher risk for prematurity (<37 weeks of amenorrhoea) in IVF pregnancies compared with ICSI pregnancies (12.4 versus 9.2%, OR = 1.39, 95% CI = 1.15-1.70). For twin pregnancies, differences were not statistically different except for a higher incidence of stillbirths in the ICSI group (2.08 versus 1.03%, OR = 2.04, 95% CI = 1.14-3.64). Intrauterine growth retardation with or without pregnancy-induced hypertension was observed more often in the ICSI group. Regression analysis of the data with correction for parity and female age showed similar results for twins. For singletons, this analysis showed similar results with the exception of low birth weight babies (<2500 g), which were also observed more often in IVF pregnancies (9.6 versus 7.9%, OR = 0.79, CI = 0.65-0.98, P = 0.03). This large case-comparative retrospective analysis showed that the obstetric outcome and perinatal health of IVF and ICSI pregnancies is comparable.

Research paper thumbnail of Outcome after elective labor induction in nulliparous women: A matched cohort study

American Journal of Obstetrics and Gynecology, 2002

To determine whether elective induction of labor in nulliparous women is associated with changes ... more To determine whether elective induction of labor in nulliparous women is associated with changes in fetomaternal outcome when compared with labor of spontaneous onset. All 80 labor wards in Flanders (Northern Belgium) comprised a matched cohort study. From 1996 through 1997, 7683 women with elective induced labor and 7683 women with spontaneous labor were selected according to the following criteria: nulliparity, singleton pregnancy, cephalic presentation, gestational age at the time of delivery of 266 to 287 days, and birth weight between 3000 and 4000 g. Each woman with induced labor and the corresponding woman with spontaneous labor came from the same labor ward, and they had babies of the same sex. Both groups were compared with respect to the incidence of cesarean delivery or instrument delivery and the incidence of transfer to the neonatal ward. Cesarean delivery (9.9% vs 6.5%), instrumental delivery (31.6% vs 29.1%), epidural analgesia (80% vs 58%), and transfer of the baby to the neonatal ward (10.7% vs 9.4%) were significantly more common (P &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;.01) when labor was induced electively. The difference in cesarean delivery was due to significantly more first-stage dystocia in the induced group. The difference in neonatal admission could be attributed to a higher admission rate for maternal convenience when the women had a cesarean delivery. When compared with labor of spontaneous onset, elective labor induction in nulliparous women is associated with significantly more operative deliveries. Nulliparous women should be informed about this before they submit to elective induction.

Research paper thumbnail of Perinatal outcome of pregnancies after assisted reproduction: A case-control study

American Journal of Obstetrics and Gynecology, 1999

We conducted a case-control study of all pregnancies obtained with assisted reproduction technolo... more We conducted a case-control study of all pregnancies obtained with assisted reproduction technology in the Dutch-speaking part of Belgium from 1992 until 1997 to investigate differences in peripartum obstetric events and the perinatal outcome. Three thousand fifty-seven singleton and 1241 twin pregnancies were studied. About 90% of pregnancies resulted from in vitro fertilization; the remainder resulted from intracytoplasmic sperm injection. Control subjects were selected from a regional register and were matched for maternal age, parity, fetal sex, plurality, and date of delivery. The main outcome measures were duration of gestation, birth weight, perinatal death, perinatal morbidity, incidence of congenital malformations, and incidence of cesarean delivery. Odds ratios and 95% confidence intervals were 2.6 (1.4-4.8) for perinatal mortality, 3.5 (2.2-5.7) for birth before 33 weeks of gestation, and 1.7 (1.5-1.9) for cesarean delivery in singleton pregnancies that resulted after in vitro fertilization. Twin pregnancies obtained with in vitro fertilization, on the contrary, were similar for all outcome measures, except for the incidence of cesarean delivery (odds ratio, 1.4; 95% confidence interval, 1.2-1.7) compared with spontaneously conceived twin pregnancies. The perinatal outcome of singleton pregnancies obtained with in vitro fertilization is significantly worse than that of spontaneously conceived pregnancies, mainly because of the increased rate of preterm birth. The outcome of twin pregnancies obtained with in vitro fertilization is comparable with that of normally conceived twins. For both singleton and twin pregnancies obtained with in vitro fertilization, the incidence of cesarean delivery is increased.

Research paper thumbnail of Perinatal outcome of 12 021 singleton and 3108 twin births after non-IVF-assisted reproduction: a cohort study

Human Reproduction, 2005

Perinatal outcome of pregnancies caused by assisted reproduction technique (ART) is substantially... more Perinatal outcome of pregnancies caused by assisted reproduction technique (ART) is substantially worse when compared with pregnancies following natural conception. We investigated the possible risks of non-IVF ART on perinatal health. We conducted a retrospective cohort study with two exposure groups: a study group of pregnancies after controlled ovarian stimulation (COS), with or without artificial insemination (AI), and a naturally conceived comparison group. We used the data from the regional registry of all hospital deliveries in the Dutch-speaking part of Belgium during the period from January 1993 until December 2003 to investigate differences in perinatal outcome of singleton and twin pregnancies. 12 021 singleton and 3108 twin births could be selected. Naturally conceived subjects were matched for maternal age, parity, fetal sex and year of birth. The main outcome measures were duration of pregnancy, birth weight, perinatal morbidity and perinatal mortality. Our overall results showed a significantly higher incidence of prematurity (<32 and <37 weeks), low and very low birth weight, transfer to the neonatal intensive care unit and most neonatal morbidity parameters for COS/AI singletons. Twin pregnancies resulting from COS/AI showed an increased rate of neonatal mortality, assisted ventilation and respiratory distress syndrome. After excluding same-sex twin sets, COS/AI twin pregnancies were at increased risk for extreme prematurity and very low birth weight. In conclusion, COS/AI singleton and twin pregnancies are significantly disadvantaged compared to naturally conceived children.