Preterm labour: recent advances in understanding of pathophysiology, diagnosis and management

The extracorporeal perfusion of the swine uterus as an experimental model: The effect of tocolytic drugs

OBJECTIVE

Comparison of the effect of tocolytic drugs on isolated swine uterus preparations.

STUDY DESIGN

Forty swine uteri were perfused with the aim to preserve a viable organ, which should be responsive to oxytocic hormones and tocolytic pharmaca. An intrauterine catheter recorded the pressure changes. After initiation of rhythmical uterine contractions we administered known tocolytic drugs (fenoterol, ritodrine, terbutaline, propofol, acetylsalicylic acid, alcohol, atosiban, verapamil, and glyceryl trinitrate) in various concentrations.

RESULTS

Perfusate pH and lactate, partial oxygen and carbon dioxide tensions, and oxygen saturation in the perfusate showed good preservation of the organ for up to 8h. All substances showed a tocolytic effect on the swine uterus. The effect varied substantially with regard to the length of the contraction free intervals, which was our main effect parameter. Fenoterol, acetylsalicylic acid, and alcohol showed the most and glyceryl trinitrate the least powerful effect.

CONCLUSIONS

A direct comparison of various tocolytic substances in the same experimental model showed the best effect for fenoterol. Furthermore, we could demonstrate that the swine uterus perfusion system is a suitable model to study the influence of various conditions like the administration of drugs or the induction of oxidative stress on the uterus function.

Precursors of Preterm Birth: Comparison of Three Ethnic Groups in the Middle East and the United States

OBJECTIVE

To examine factors related to preterm birth in three ethnic groups and in three different countries.

DESIGN

Data were obtained on a convenience sample of 118 Lebanese mothers, 104 Egyptian mothers, 40 Mexican American mothers, and 32 White American mothers from Southern California. About half of each cohort had delivered a preterm newborn and half a full-term newborn. Mothers with premature or full-term newborns completed a questionnaire by interview. Analysis compared ethnic groups and preterm- versus full-term birth groups. Multiple logistic regression determined relatedness to outcome.

RESULTS

Descriptive factors differed among groups, but not for preterm versus full-term newborn groups. Significant factors for premature birth were vaginal infections, stress, smoking, drug use, and protein intake. Factors significantly related to preterm birth in the Middle-Eastern and American groups were almost identical: social support, stress, and exercise. Smoking was related only in the American group.

CONCLUSIONS

These data suggest risk factors are similar across nations and ethnic groups. Prenatal counseling and programs should address these four issues.

Minimal access fetal surgery

The development of fetal surgery has led to promising therapeutic options for a number of congenital malformations. However, preterm labor (PTL) and premature rupture of membranes continue to be ubiquitous risks for both mother and fetus. To reduce maternal morbidity and the risk of prematurity, minimal access surgical techniques were developed and are increasingly employed. Congenital diaphragmatic hernia (CDH), obstructive uropathy, twin-to-twin transfusion syndrome (TTTS), and sacrococcygeal teratoma have already been successfully treated using minimal access fetal surgical procedures. Other life-threatening diseases as well as severely disabling but not life-threatening conditions are potentially amenable to treatment. The wider application of minimal access fetal surgery depends on a continued improvement in technology and a better understanding of complications associated with fetal intervention.

beta2-Adrenergic receptor genotype and preterm delivery

OBJECTIVE

Our purpose was to determine whether the functional genetic polymorphisms of the beta(2)-adrenergic receptor (beta(2)AR) that result in changes in amino acid residues 16 and 27 are associated with preterm delivery.

STUDY DESIGN

A case-control study comparing the distribution of beta(2)AR genotype between 251 Hispanic women delivered at term and 28 Hispanic women delivered preterm. Preterm delivery was defined as spontaneous onset of labor resulting in delivery before 37 weeks of gestation, in a singleton pregnancy, with no apparent etiology for preterm labor and delivery. Genomic DNA was isolated from peripheral blood, and beta( 2)AR alleles were identified by established techniques.

RESULTS

Only one woman (4%) with preterm labor was homozygous for Arg16 versus 79 (31%) in the control group (P =.01, odds ratio 0.08). There was no association of preterm labor with genotype at position 27.

CONCLUSION

Our data demonstrate that homozygosity for Arg16, which in vitro is associated with decreased down-regulation of the beta(2)AR, protects from preterm delivery.

Child development after maternal tocolysis with beta-sympathomimetic drugs

The psycho-social development of both preterm and term children whose mothers reported tocolytic treatment was assessed at the ages of 2, 4.5, and 8 years. Term children exposed to tocolysis showed a higher rate of psychiatric disorders as well as poorer cognitive and motor performance than controls. In the preterm children no adverse impact of tocolysis could be found. The results are discussed concerning possible ways in which tocolytic treatment may influence child development. Restrictions because of the preliminary character of this study and the need of further prospective studies to clarify the developmental impact of tocolysis are also considered.