There has been much interest in the production of subunit vaccines against human and agricultural parasites since the early 1980s. Development of subunit vaccines requires the identification of protective antigens and their formulation with a suitable adjuvant to stimulate the immune response appropriately. References


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However, postponing premature delivery by 48 hours appears sufficient to allow pregnant women to be transferred to a center specialized for management of preterm deliveries, and thus administer corticosteroids for the possibility to reduce neonatal organ immaturity.The efficacy of β-adrenergic agonists, atosiban, and indomethacin is a decreased odds ratio (OR) of delivery within 24 hours of 0.54 (95% confidence interval (CI): 0.32-0.91) and 0.47 within 48 hours (OR 0.47, 95% CI: 0.30-0.75).Antibiotics were thought to delay delivery, but no studies have shown any evidence that using antibiotics during preterm labor effectively delays delivery or reduces neonatal morbidity. Antibiotics are used in people with premature rupture of membranes, but this is not characterized as tocolysis. Contraindications to tocolytics
In addition to drug-specific contraindications, several general factors may contraindicate delaying childbirth with the use of tocolytic medications. Fetus is older than 34 weeks gestation
Fetus weighs less than 2.5 kg, or has intrauterine growth restriction (IUGR) or placental insufficiency
Lethal congenital or chromosomal abnormalities
Cervical dilation is greater than 4 centimeters
Chorioamnionitis or intrauterine infection is present
Pregnant woman has severe pregnancy-induced hypertension, severe eclampsia/preeclampsia, active vaginal bleeding, placental abruption, a cardiac disease, or another condition which indicates that the pregnancy should not continue. Maternal hemodynamic instability with bleeding
Intrauterine fetal demise, lethal fetal anomaly, or non-reassuring fetal status

Future direction of tocolytics
Most tocolytics are currently being used off-label. The future direction of the development of tocolytics agents should be directed toward better efficacy in intentionally prolonging pregnancy. This will potentially result in less maternal, fetal, and neonatal adverse effects when delaying preterm childbirth.