The main concern of mothers is not the effect of contraction suppressants on themselves, but the main fear of affecting their babies, so we will talk about the immediate and long-term effects of various contraction suppressants on babies for your reference! 1, the effectiveness of contraction inhibitors First of all, once again: contraction inhibitors can only suppress acute contractions for a short period of time, and cannot eliminate the underlying factors that trigger contractions, nor can they reverse the changes in labor that have already occurred, such as a shortened cervix that has been tolerated, such as a dilated uterus. Contraction inhibitors can neither lengthen a shortened cervix nor allow a dilated cervix to close completely again. Theoretically, it is only to fight for those 48 hours or so to promote fetal lung maturation and for the baby to be transferred to a safer medical center. So people will ask me: Dr. Liu, why do you also use contraction suppressants? That depends on different situations, for example, more definite cervical insufficiency where the cervix may not be able to tolerate this physiological contraction, such as emergency cervical cerclage where the uterus is already open and we have to do a good postoperative contraction management. However, a combination of safety and efficacy needs to be selected and monitored in a targeted manner, and patients found to be intolerant or to have side effects are promptly replaced. Of course, the most critical thing is to master the indications for use. If economic conditions allow and clinically necessary, atosiban should be preferred, after all, there are few side effects and no clear contraindications to its use, but it is too expensive for everyone to afford. 2, the safety of uterine contraction inhibitors Ampoule (Ritodrine): is the most commonly used, but also the most worried, because its side effects are more common and obvious, such as panic, hand tremors, pregnant women feel, but also know that the fetal heart rate will be accelerated. The main effects of the drug on the fetus/newborn are fetal tachycardia and neonatal hypoglycemia, but the acid-base balance of the fetus is not affected. For the possibility that long-term use of the drug may cause sympathetic-parasympathetic nervous system imbalance in newborns, no such association has been found in animal studies and human observational studies to date. Some guidelines no longer recommend the use of Ampro as a first-line contraction inhibitor, more for its side effects on the pregnant woman than for the fetus, especially if it causes maternal cardiopulmonary, metabolic, and electrolyte disturbances, etc. It is important to monitor the use, especially in twin pregnancies with a heavy cardiopulmonary burden, with caution and good monitoring. Cardiac pain (nifedipine): animal studies suggest that this drug may reduce uterine artery blood flow and fetal oxygen supply, but ultrasound monitoring of fetal blood flow including umbilical artery, and uteroplacental blood flow did not reveal any abnormalities. Monitoring of fetal acid-base balance by umbilical blood or transdermal blood was normal and no abnormalities were found. As a reminder, sublingual administration of cardiac painkillers is not recommended and oral administration is recommended. Therefore, its current use is relatively safe for fetuses or newborns. Together with the fact that it may be beneficial for some serious complications in preterm infants, possibly due to other contraction inhibitors, it is used as a first-line contraction inhibitor. Indomethacin (anti-inflammatory pain): mainly premature ductus arteriosus and amniotic fluid reduction. Premature ductus arteriosus depends mainly on the week of gestation and the time of administration, so short-term use is recommended (within 1 week in Chinese textbooks, within 48 hours in Chinese preterm birth guidelines, and within 48-72 hours in relevant US views) and is not recommended after 32 weeks. One study followed more than 500 cases of short intrauterine exposure to indomethacin and did not find this complication. Because the drug reduces amniotic fluid by decreasing renal blood flow, it can be used to treat excessive amniotic fluid before 32 weeks. The immediate and long-term effects on the newborn are not known. Epro (Atosiban): The biggest side effect of this drug mentioned earlier is that it is expensive, and it is currently considered safe for the mother and child with no clear contraindications. However, the US FDA has not recognized the effectiveness of this drug in preventing preterm labor by suppressing contractions before 28 weeks, so the drug is not much used in the US and is widely used in Europe. Interestingly, the only FDA-approved contraction suppressant used to inhibit contractions to prevent preterm labor is instead Ampro. But now, due to its too many side effects, it has also been gradually relegated to second-line use. Magnesium sulfate: Pregnant women who have used it should be well aware of the hot flashes, flushing, nausea, dizziness and discomfort, but the effect on the fetus mainly lies in lowering the baseline fetal heart rate and reducing the variability, but it does not cause fetal hypoxia, assessing the changes in the fetus after the use of magnesium sulfate in pregnant women, there are no significant abnormalities in biophysical scores and fetal monitoring. The main reason why it is no longer recommended for the prevention of preterm labor by suppressing contractions is the possibility of fetal/neonatal alterations in serum calcium, magnesium and phosphorus after 5-7 days of continuous use, resulting in bone loss, as suggested by the FDA. Therefore, it is not recommended. 3, again about the reliability of the evidence Some people ask me, Dr. Liu, why do you keep referring to foreign data? I would prefer to cite Chinese data, so that it is more informative for our domestic pregnant women, but unfortunately China often lacks relevant data! Look at this literature, when it comes to the effectiveness of indomethacin, it is suggested that indomethacin can reduce the rate of preterm birth at 48 hours as well as at 7 days, and the evidence comes from surprisingly from a study of 30 pregnant women with symptoms of preterm birth. These 30 cases were randomly assigned to a treatment group and a placebo group. Thirty cases? Yeah, just 30 cases you wouldn’t normally allow me to do. You say, you have contractions, you line up for a doctor’s appointment, and the doctor asks you to draw a lot, and what you get may be a drug or a vitamin tablet, do you think you’ll come after me? I really want to try to be a doctor abroad to see how these patients agree, I believe that absolutely not money can solve the problem. Unfortunately, there is no chance in this life, poor English, even the only thing that will be interspersed with dialect of Mandarin. Then, we are faced with which studies to believe, small sample size, ethical issues, retrospective studies, different populations included for example different possible causes of preterm labor symptoms, the presence of various possible biases causing unreliable results, and so on. Therefore, the evidence is constantly updated, the guidelines are constantly updated, and the direction of our clinical care is constantly changing with it! I always look forward to the day when you allow me to do a randomized controlled study of the cervical tray so that we have better evidence to confirm whether it works or not? Of course, these studies must be carried out ethically, must be signed by your consent to proceed. 4, again about magnesium sulfate In fact, for its effectiveness, many studies do not deny that it is not found to be worse than other contraction inhibitors. But more due to its side effects, especially on the fetus after 7 days of continuous use, is why more guidelines do not recommend its use as a contraction suppressant drug. Not only this drug, but other drugs as well, Epro is not found to be more effective than other drugs to prolong longer gestational weeks, but it is relatively safe. The rationale for recommending indomethacin and cardiac painkillers is also more based on safety, patient tolerance, and ease of use. When studies find that a currently recommended drug has more side effects, it will always be discouraged or even eliminated.