Optimal Timing of Delivery Based on the Risk of Stillbirth and Infant Death Associated with Each Additional Week of Expectant Management in Multiple Pregnancies: a National Cohort Study of Koreans

BACKGROUND

The purpose of this study was to compare the fetal/infant mortality risk associated with each additional week of expectant management to that associated with immediate delivery in women with multiple gestations.

METHODS

This was a retrospective national cohort study of 94,170 multiple deliveries, 92,619 (98.4%) twin and 1,352 (1.44%) triplet pregnancies, between 32 0/7 and 42 6/7 weeks of gestation recorded in the Korean vital statistics database. We investigated the risks of stillbirth and infant death after birth in Korea according to the week of gestation in twin and triplet pregnancies.

RESULTS

The risk of stillbirth significantly increased between 34 and 35 weeks of gestation and between 37 and 38 weeks of gestation in twin pregnancies and between 34 and 37 weeks of gestation in triplet pregnancies. The risk of infant death following delivery gradually decreased as pregnancies approached full term. Week-by-week differences were statistically significant between 33 and 34 weeks, with decreasing risks of infant death at advancing gestational ages in twin pregnancies. At 37 weeks of gestation, the relative risk of mortality was significantly higher with expectant management compared with immediate delivery (relative risk, 3.00; 95% confidence interval, 1.41-6.38).

CONCLUSION

In twin pregnancies, delivery at 37 weeks of gestation can minimize the risks of stillbirth and infant death in uncomplicated cases, although individual maternal and fetal characteristics must be considered when determining the optimal timing of delivery. In multiple pregnancies, close fetal surveillance is needed after 34 weeks of gestation.

Tobacco smoking and twinning

In a case-control study an association was found between mothers' smoking habits and the frequency of dizygotic twinning. As cases were included all twins born in Denmark in 1984 and 1985. A random sample of 1.5% of mothers to singletons, born in the same period were selected as controls. Only live-borns, conceived after no hormonal treatment, were included in the study. The finding may be due to the well-known anti-estrogen effect of smoking.

The effect of pregnant mare serum gonadotrophin and human chorionic gonadotrophin on ovulation and on fertility in the ewe

An experiment involving 300 cyclic Merino ewes and designed to study the effects of pregnant mare serum gonadotrophin (PMSG) and human chorionic gonadotrophin (HCG) on ovulation and subsequent fertility is described. PMSG (750 i.u.) was given on the 12th day of the oestrous cycle and HCG (400 and 800 i.u.) was injected intravenously within 3 hr of the onset of oestrus. PMSG induced multiple ovulation and hastened the time of ovulation in relation to the onset of oestrus by 2-3 hr, but did not enhance the precision of the time of ovulation. HCG had no effect upon the time of ovulation but did increase the proportion of follicles which ruptured. Neither PMSG nor HCG, alone or in combination, adversely affected fertility. In fact, HCG increased the proportion of ewes which lambed. Both PMSG and HCG increased the incidence of multiple births. The effect of PMSG on the incidence of multiple births was a direct reflection of its ability to induce multiple ovulation. HCG given alone, or after PMSG increased the incidence of multiple births but its effect was less marked than that of PMSG, and unlike that of PMSG the effect of HCG did not appear to be solely due to an increase in the number of ovulations.

Is there an indication for embryo reduction?

The selective reduction of embryos in multiple pregnancies poses numerous medical, technical, ethical and psycho-social problems. In a retrospective study, we analysed nine hundred and twenty-two pregnancies obtained using medically assisted procreation between May 1982 and May 1990. Among 922 successful pregnancies, 372 were singleton, 102 were twin and 13 were triplet. Data from this analysis and from a French multicentre study of 262 embryo reduction procedures demonstrated the value of an embryo quality score for minimizing the risk of multiple pregnancy and the existence of extremely infrequent, ethically acceptable indications for embryo reduction. These indications included ultrasound-proven malformations of one fetus, multiple pregnancies in patients with extensive uterine scarring, and multiple pregnancy despite the appropriate use of preventative measures which can be expected to make this technique unnecessary in the future.

Multifetal pregnancy reduction: comparison of obstetrical results with spontaneous twin gestations

Thirty-two multifetal pregnancies were reduced to twin gestations. Our control group was composed of 32 spontaneous twin gestations. The comparison of these two groups did not show that the procedure altered obstetrical results as far as duration of gestation, birth weight and rate of dismaturity are concerned.

Selective reduction in multifetal pregnancies: technical and psychological aspects

OBJECTIVE

To evaluate efficiency and safety of a very early transvaginal selective reduction procedure in multifetal pregnancies.

DESIGN

Prospective study.

SETTING

Obstetric and Gynecology Department, University of Paris VI.

PATIENTS

Twenty-two patients with multifetal pregnancies: 14 triplets, 8 quadruplets, and 1 quintuplet.

INTERVENTION

Selective embryonic reduction was performed at 7 weeks of amenorrhea under general anesthesia by transvaginal embryo puncture and aspiration. Two embryos were left in place.

MAIN OUTCOMES

Pregnancy outcome (immediate or delayed complication, term of delivery, newborns) and psychological impact.

RESULTS

No complication occurred. The 22 patients now have delivered at 36.5 weeks of amenorrhea, on average giving birth to 44 neonates with no congenital malformation. If the procedure generates anxiety, it is nevertheless perceived as necessary for the successful outcome of the pregnancy.

CONCLUSION

Early mechanical transvaginal embryo reduction performed at 7 weeks of amenorrhea, leaving two embryos is, in our opinion, a simple and safe procedure with no affect on remaining fetuses. It is necessary when there are four or more embryos, and it should also be proposed for triplets. In these circumstances, patients saw reduction as a necessary procedure.

Chorionic villus sampling and selective termination of a chromosomally abnormal fetus in a triplet pregnancy

Transabdominal chorionic villus sampling (CVS) was performed on a patient with a triplet pregnancy. The karyotypes were as follows: 46,XX; 46,XY; and 46,XY/47,XXY. Selective termination was done on the affected fetus successfully by intrathoracic potassium chloride (KCl) injection. Amniocentesis which was performed at the same time confirmed the CVS results, showing the same mosaic findings. Following the procedure, the pregnancy proceeded uneventfully and two normal newborns were delivered at term.

Delayed interval delivery of two remaining fetuses in quintuplet pregnancy after embryo reduction: report and review of the literature

A case report is presented with a prolonged interval between delivery of 25 days. A quintuplet pregnancy resulted from hormonal stimulation of ovulation. Two fetuses remained after an embryo reduction was performed at 11 weeks gestation. At 22.5 weeks gestation the first twin (310 g) was delivered after spontaneous rupture of membranes. Using tocolytic agents, the second twin (710 g) was born at 26 weeks of gestation. This case is discussed and a review of the literature is given.

Ruptured ectopic pregnancy in a patient with a recent intrauterine abortion

The case of a 33-year-old woman who presented with abdominal pain referable to the lower abdomen is discussed. She had had an uncomplicated intrauterine abortive procedure two weeks earlier. It was determined that a ruptured ectopic pregnancy was the etiology of her abdominal pain. The rare phenomenon of combined intrauterine and extrauterine pregnancy is discussed.

Perinatal mortality rate in a south Indian population

Perinatal mortality rate was assessed for 13964 consecutive births in SAT Hospital, Trivandrum, South India, during a period of one year. The overall perinatal mortality rate was 42.75, stillbirth rate 24.41 and early neonatal mortality rate 18.79. The perinatal mortality rate in multiple pregnancy was 156.65. Preventable causes of perinatal mortality still make a major contribution to perinatal deaths in developing countries.

Pregnancy and the risk of developing rheumatoid arthritis

There have been conflicting reports on, and no plausible biologic explanation for, a protective effect of oral contraceptive (OC) use on the development of rheumatoid arthritis (RA). Therefore, we investigated aspects of behavior related to OC use that could explain the preventive effect of OC on the onset of RA. In the present case-control study, past pregnancy, age at first pregnancy, and pregnancies with adverse outcome were studied as possible risk factors for RA. Interview information on reproductive variables was obtained from 135 young adult women with confirmed definite or classic RA of recent onset, and from 378 control patients with soft tissue rheumatic disorders or osteoarthritis. All patients had at least 2 years of followup to confirm the consistency of the diagnosis. We found a decreased risk of RA in women who had been pregnant. The risk of RA in women who had ever been pregnant compared with women who had never been pregnant was 0.49 (95% confidence interval 0.27-0.91). The earlier the first pregnancy, the lower the risk of RA. Pregnancy with adverse outcome (i.e., gestation less than 25 weeks) did not substantially change the risk of RA (relative risk 0.73, 95% confidence interval 0.50-1.07). The protective effect of pregnancy was independent of OC use, the presence of HLA-DR4, or a family history of RA. Immune modulation by female hormonal influences could be an explanation for the results of the present study.

Selective reduction in multiple gestation

As new advances in the treatment and management of infertility become available, it is hoped that selective reduction procedures will no longer be necessary. In the interim, however, it is imperative that nurses be knowledgeable about the options available to parents experiencing multifetal pregnancy, including the choice of selective reduction procedures.

Fetal exsanguination following intrauterine angiographic assessment and selective termination of a hydrocephalic, monozygotic co-twin

Selective termination by intracardiac potassium chloride injection was performed in twins discordant for hydrocephaly at 20 weeks' gestation. Because of the potential for vascular anastomoses to exist between the twins, fetal angiography was performed prior to the selective termination procedure. Determination of vascular connections between the fetuses was hindered by fetal bradycardia following intracardiac administration of contrast material. Selective termination was performed without difficulty using intracardiac potassium chloride (KCl) to produce asystole in the twin with hydrocephaly. The unaffected fetus appeared active and had a normal heart rate during and immediately after the procedure. However, both twins were found to have died the following day. Pathologic examination documented several vascular anastomoses between the monochorionic, diamniotic fetuses. A likely cause of death was exsanguination of the normal twin into the abnormal one. This case illustrates the difficulties encountered in selective termination of monozygotic twins and, to our knowledge, represents the first reported use of intrauterine fetal angiography.

Selective termination of multiple gestations

Twenty-two selective terminations in multiple gestations were performed by a number of different methods. In 17 dichorionic pregnancies there was a successful delivery in surviving singletons or twins. In five monochorionic pregnancies undergoing selective termination there was a successful delivery in only one and a pregnancy loss in the other four. Six of the 18 delivered pregnancies were complicated by premature labor and delivery. Among the several methods used for selective termination, intracardiac potassium chloride injection appears to be the procedure of choice in dichorionic pregnancies.

Breech births in twin pregnancy: an analysis of Apgar score and perinatal mortality from a Nigerian sample

Perinatal mortality (PNM) rates are reported for 146 twin-1 and 192 twin-2 breech births among 622 consecutive twin pairs delivered at the University of Ilorin Teaching Hospital, Ilorin, Nigeria. Stillbirths and infants with severe asphyxia (Apgar score 1-3) were recorded in significant proportions of both first and second twin breech infants. PNM rates were 13.7% twin-1, 18.8% twin-2; corrected PNM for infants weighing 2.0 kg or more, were 9.3% and 12.4% for twin-1 and twin-2, respectively. Twin specific breech PNM decreased with increasing birthweight of first and second twin to a low optimum in the weight group 2.5-2.9 kg, and thereafter rose for both first and second twin with birthweight 3.0 kg and above. Factors such as low birthweight, breech/breech presentation, breech extraction and retained second twin breech contributed significantly to the high PNM rates. More favorable PNM rates were recorded among a limited number of breech infants delivered by primary cesarean section for breech/breech or first twin breech presentations. A liberal approach to cesarean section delivery for breech twin births, and particularly for paired breech/breech presentations is strongly advocated.

Multiple pregnancy as a risk factor in rural Tanzania

The prevalence of twin pregnancies in two rural hospitals in the South Western Highlands of Tanzania ranged from 15 to 20 per 1,000 births. The literature on the generally assumed high twinning rates in the whole of Africa is reviewed. High prevalence figures can be the result of hospital selection, as most African studies are hospital-based. Only from Nigeria, one population-based study revealed a rate of 45 per 1,000. In both hospitals perinatal mortality in twin births was strikingly low, especially when birthweight was at least 1,500 g: between 30 and 40 per 1,000 births. It is argued that there is no place for a more liberal use of caesarean section to further reduce perinatal mortality.

[[Analysis of multiple birth rates in Japan]]

The author analyzes multiple birth rates in Japan based on data from published vital statistics for the years 1951-1968 and from computer files for 1974-1985. "The higher multiple birth rate since 1974 was attributed to the higher proportion of mothers treated with ovulation-inducing hormones in Japan." (SUMMARY IN ENG)

Perinatal factors in twin mortality in Nigeria

The results of a retrospective study involving 622 twin-pairs born over an 18-month period among 17,726 births at the University of Ilorin Teaching Hospital, Ilorin, Nigeria, are presented with particular reference to four variables: birthweight, presentation, parity, and intertwin delivery time interval. The twinning incidence was 35.1 per 1000. Monozygous and dizygous rates are 7 and 28 per 1000, respectively. Overall perinatal mortality (PNM) was 15.5%. Mortality was higher in second than in first twin (19.5% vs. 11.6%), and consistently higher when divided into birthweight groups. Corrected PNM increased with breech presentations: 16.3% in breech:breech compared with 3.9% in vertex:vertex presentations. The twinning rate increased with parity; PNM is low in parity 1, of little variation in birth-ranks 2-5, and high in para 6 and above. Delivery of the second twin within 15 min seems optimal, giving a corrected PNM 3.6% in contrast to rates of 10.1%, 14.0% and 19.1%, respectively when delivery occurred between 16 and 30, 31 and 60 and greater than 60 min, respectively. Prevention of preterm delivery, increased use of cesarean section delivery for malpresentation, active management of delivery of second twin within an optimal time of 15 min, and family planning are suggested in order to decrease twin PNM.

A study of the influence of ovulation stimulants and oral contraception on twin births in England

A study of 111 mothers of twins in Nottinghamshire, England, in 1981-82 showed that at least 12 had used ovulation stimulants, compared to 2 of 102 mothers of singletons. Thus, the use of ovulation stimulants increased the twinning rate of this population by about 10 percent; this may explain the recently noted levelling off in the secular decline in twinning rates. In contrast to a recent study in France, no association between twinning and prior use of oral contraceptives was seen.

The ghost artifact

A ghost artifact is produced when refraction of an ultrasound beam occurs in one part of a scanning plane. Image duplication or even triplication may result. This may lead to error of diagnosis and measurement. Ghost artifacts are commonly seen in transverse echograms of pelvic organs because the rectus muscle interposed between the transducer and the area of interest is acting as a lens and refracts the ultrasound beam. Three illustrative case reports are presented.

Association of birth outcome with subsequent fertility

The association between birth outcome and subsequent fertility was analyzed by using linked Norwegian birth certificates. All births of order 1, 2, and 3 which occurred during 1967 through 1974 were considered index births; there were approximately 207,000 index births of order 1, 165,000 of order 2, and 87,000 of order 3. The mothers' fertility after these index births was summarized with a life-table technique. Fertility was most pronounced if there were no survivors of an index birth, intermediate if there was one survivor, and lowest if both members of a set of twins survived. Advanced maternal age was associated with markedly reduced fertility. The sex of a surviving singleton had little effect on a mother's subsequent fertility. However, there was a sex-related difference if index twins survived; fertility was lower after the birth of unlike-sex twins and higher after the birth of like-sex twins. This probably reflects reproductive limitation rather than a differential fecundity for mothers of dizygotic and monozygotic twins. A comparison of fertility after births of like-sex and unlike-sex twins with one survivor may indicate that mothers of dizygotic twins were more fertile, but the number available for study was small. Reproduction among women who had two index births during 1967 through 1974 was examined separately. Fertility was most marked if neither of the first two infants survived and lowest where three survived (i.e., where one of the index births involved twins). If there were two survivors, the sex composition of the pair influenced fertility; fertility was greater if the two survivors were of the same sex and lower if they were of unlike sex. Since a woman who has an unfavorable outcome in one pregnancy will be at a higher risk of having an unfavorable outcome in a subsequent pregnancy, the higher fertility of such women will, to some degree, inflate the frequency of unfavorable outcomes in a population of births.

Gender after artificial induction of ovulation and artificial insemination

Several studies on artificial insemination by donor (AID) semen have suggested that the gender of infants can be influenced by treatment of the women with clomiphene citrate (CC) and by the type of semen used (fresh versus cryopreserved). We conducted a 3-year prospective clinical trial to test these hypotheses. Two groups of pregnant women were evaluated. Group I (n = 130) comprised women whose ovulation was induced by CC; group II (n = 190) comprised those who conceived during spontaneous ovulatory cycles. In a total of 320 pregnancies, 55 spontaneous abortions occurred, 23.1% in group I and 13.2% in group II (P less than or equal to 0.05). Two tubal ectopic pregnancies occurred in group I. Of the 100 and 165 pregnancies carried to term in the treated and control groups, respectively, 11% and 1.8% involved twins (P less than or equal to 0.005). When only single births were considered, group I had 46.1% males in 89 term pregnancies, and group II had 60.5% males in 162 term pregnancies. Significantly more female offspring occurred in the group treated with CC (P less than or equal to 0.05). Because it is possible that a portion of the effects observed in this study were a function of cryopreservation of the AID semen, we compared data on frozen sperm with data on fresh sperm in terms of abortion, gender, and incidence of multiple births; there were no significant differences. Fertil Steril 40:481, 1983.

Trends in perinatal mortality at a Hong Kong hospital

Causes of perinatal mortality at Tsan Yuk Hospital, Hong Kong, were classified into 14 categories from the "P" list of stillbirths and neonatal mortality in the International Statistical Classification of Diseases, Injuries and Causes of Death. Trends for each category over the period 1970-1979 were examined by regression analysis. Overall perinatal mortality fell from 17.80 in 1970 to 10.94 in 1979. A low incidence of deaths from congenital abnormality and medical complication in the mother was observed. Significant statistical correlations were obtained in the trends in mortality associated with placental hemorrhage, pre-eclampsia, difficult labor, hemolytic disease of the newborn, and prematurity. Improvements in perinatal mortality in these areas as well as inadequacies in perinatal care in other areas, are discussed.

Spontaneous abortion incidence in the treatment of infertility

Analysis of published series indicates that, irrespective of the method of data collection, close agreement exists on empirically derived incidences of spontaneous abortion in North American populations, provided that age, previous abortion history, and gravidity are controlled. The normal incidence of clinically apparent abortion among first pregnancies in women under age 30 years is in the range 8.3% to 11.0%. A comprehensive analysis of published series on pregnancies after infertility treatment indicates that only three therapeutic methods are attended by an abortion incidence that approaches this asymptote: ovulation induction with bromocriptine in hyperprolactinemic anovulation (11.8%; n = 1,233 pregnancies); artificial insemination with donor semen for azoospermia (11.4%; n = 326 first pregnancies); and operation for endometriosis (9.3%; n = 768 pregnancies). Abortion incidences accompanying other modes of therapy are higher. Because increased abortion incidence is not generally recognized as a specific reproductive difficulty in infertile couples, as are the other two: i.e., refractory infertility despite technically adequate therapy and ectopic pregnancy, plausible physiologic mechanisms for abortions in specific categories of disease or treatment type are described and discussed in detail. Moreover, abortion incidence is proposed to be a sensitive and objective parameter with which to assess distortions in human reproductive physiology, especially when competing methods of infertility treatment have overall pregnancy outcomes that are thought to be similar.

Vaginal spermicides and outcome of pregnancy: findings in a large cohort study

By the end of 1980, 5729 singleton planned pregnancies, 1552 singleton unplanned pregnancies, and 81 multiple pregnancies had been observed among the 17032 participants in the Oxford-Family Planning Association contraceptive study. The outcome of these pregnancies was investigated in relation to the use of vaginal spermicides. There was some suggestion that spermicide use might have a small adverse effect on the risk of congenital malformations, especially among infants conceived as a result of contraceptive failure. There was not, however, any evidence of any other adverse effect of spermicide use. In particular, the results provide strong evidence against the hypothesis that spermicide use has any appreciable effect on the risk of spontaneous abortion.

Multiple pregnancy and fetal abnormalities in association with oral contraceptive usage

1,000 multiple births were examined in relation to maternal exposure to an oral contraceptive before conception. There was a significantly higher rate of monozygotic twinning among pregnancies which took place within 6 months of cessation of the contraceptive. In the monozygotic group there was a significant increase in the incidence of congenital abnormalities (P less than 0.01) when conception occurred within 3 months of cessation of the contraceptive.

Monitoring of ovulation induction with human menopausal gonadotropin and human chorionic gonadotropin by ultrasound

Ovarian follicular growth was monitored by ultrasound and plasma estradiol levels in 43 cycles of 27 patients. These women were treated with human menopausal gonadotropin (hMG) and human chorionic gonadotropin (hCG) for anovulation or poor cervical mucus. Ultrasonography can help to prevent multiple pregnancies by allowing the withholding of the ovulatory injection of hCG if the number of mature follicles is too great. Nevertheless, mild to moderate hyperstimulation cannot always be prevented; it is sometimes the price one has to pay to obtain a pregnancy. Giving a direct view of follicular maturation, this method can be helpful in the determination of the best time for the induction of ovulation.

Triplet pregnancies

Fifteen triplet gestations delivered over 23 years beginning with 1954 are reviewed. The mortality rate was 7.1% in the gestation period of 28 weeks or more. This mortality rate compares favorably with the 15% to 50% rate reported in the literature. Among the third babies of each set, there was a mortality rate of 14.3%, again confirming the high mortality rate reported in the literature. Morbidity in triplet gestations was equally elevated. Although the data do not suggest what the best method of delivery is, the increased morbidity and mortality for the third baby of the set delivered vaginally implies that a more liberal use of cesarean section may reduce the potential risks for that baby. Also, among the eight cesarean sections performed in pregnancies at 28 weeks of gestation or more that have been reported in the literature, none of the babies died during the neonatal period.

The use of gonadotropins for induction of ovulation

There has been impressive progress in the treatment of anovulation with gonadotropins in the last two decades. At the present time most patients can be helped. The treatment is expensive and complicated. To obtain good results with the fewest complications, patients should be closely monitored by measuring urinary or plasma estrogen levels, and treatment should be given only in centers where the estrogen assay is readily available. Severe hyperstimulation is avoidable, but the high rate of multiple gestations remains unavoidable. Possibly with sonographic monitoring of follicular development this problem will be solved.

Multiple births in Hausa women

The incidence of multiple births was studied using the maternity records of 5750 Hausa women living in the savannah zone of Nigeria. There were 40 twins and 2 triplets/1000 births. Twenty six per cent of twins were monozygous. The incidence of multiple births, which was about five times higher than that observed in any western population, was significantly lower than that of other ethnic groups, who live in the hot and humid climate of the southern pat of country. The incidence of multiple births was related to maternal age but did not bear any association to the climate or prevalence of malaria.

[The outcome in pregnancies resulting after the induction of ovulation 519 pregnancies (author's transl)]

Some geneticists have been against induction of ovulation because there is a greater incidence of chromosome abnormalities in spontaneous abortions that occur after induced pregnancies. We have found the number of early abortions (15.6 p. 100) and of malformed fetuses (4.8 p. 100) is not greater than average when we have studied a personal prospective series of 140 pregnancies and a series of 519 pregnancies collected following an enquiry made among some of our colleagues. The number of late abortions and of premature labours is much higher (3.4 p. 100 and 14.8 p. 100 respectively) and they correspond particularly with the higher incidence of multiple pregnancies (12.3 p. 100) which have been obtained especially after the use of HMG. This has a direct repercussion on perinatal mortality (4.3 p. 100).

Outcome of pregnancy after clomiphene therapy

Of 159 pregnancies conceived after clomiphene therapy, 141 ended in childbirth, including seven sets of twins. There was a probable increase in the number of infants born with major malformations. These were exclusively to women who had not previously borne a normal infant. The incidence of malformed infants compares well with that published after gonadotropin therapy. The possibly higher incidence of malformations seen after drug-induced ovulation would therefore seem to be due to the underlying subfertility state and thus not a direct drug effect.