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Premature birth: causes, symptoms, therapy of preterm birth. Survival of the premature infant.

Premature birth is an event that puts mother and fetus at risk and requires adequate management. In this article I will explain the mechanisms that lead to the birth of a premature baby, the symptoms, the therapies that are used to maintain pregnancy in the event of a threat of preterm birth and the possible consequences for the fetus with an early birth.

Premature birth

Premature birth occurs when a woman gives birth to a premature baby between the 22nd week and the 37th week of pregnancy. Bringing the pregnancy to term requires a harmonious mechanism of the maternal body and the fetal body. The failure of a link in the chain can cause anomalies that can result in a threat of premature birth or with the need to anticipate delivery to safeguard the well-being of the fetus in relation to the risk-benefit of staying in the uterus. All obstetric and fetal situations that cause a risk of preterm birth require adequate pregnancy surveillance, in accordance with the guidelines, and the implementation of procedures to ensure the safety of the mother and baby. Unfortunately, in some clinical situations there is no possibility of avoiding the early birth of the fetus which results in a premature birth. Many women expect to have a physiological experience of pregnancy and the threat of an early birth is a reason for anger or a sense of guilt because the product of conception was not able to be safeguarded. Dear mom, the important thing is never to lose sight of the goal ... to bring a child into the world.

premature birth
premature birth

When is premature birth?

Pregnancy lasts approximately 40 weeks. When the newborn has completed maturation it will lead to birth in a period between the 38th week and the 42nd week of gestation. A birth that occurs between week 22 and week 36 of gestation is called a preterm birth. In turn, premature birth is divided into:

  • Late premature birth: when the fetus is born between the 34th and 37th week of pregnancy

  • Severe premature birth: when the baby is born between the 25th and 33rd week of gestation

  • Extreme premature birth: if the baby is born before the 25th week of gestation

Premature birth: when you are out of danger

The gestation period in which preterm birth occurs has a heavy weight on the risks associated with the survival and health of the premature baby. A premature baby born between the 25th and 29th week of pregnancy certainly has fewer chances of survival and a greater chance of reporting diseases related to maturity. A premature baby between the 30th and the 33rd week of pregnancy certainly has a greater chance of survival also in consideration of the great advances made by neonatal medicine. The birth of a preterm baby in these weeks will require admission to neonatal intensive care where it will be able to complete growth in a thermo-incubator. The birth of a newborn between the 34th week and the 37th week is certainly less likely to have fetal complications. The newborn is not totally out of danger, but it certainly has a greater ability to adapt to extrauterine life. Preterm birth in twin pregnancy, which in itself has a higher probability of premature birth, should also be taken into consideration. In most cases, premature twins require a period of hospitalization in the NICU For cases of births below the 23rd week of pregnancy we speak of abortion and not of the birth of a premature fetus.

Factors that increase the likelihood of premature birth

  • Smoke

  • Drug use

  • Stress

  • Obesity

  • Previous premature birth

  • Medically assisted procreation: IVF, ICSI, egg donation

  • Infections

  • Short interval between pregnancies.

Causes of premature birth

As mentioned, early birth is defined as any birth that took place before 36 weeks and 6 days, essentially when you give birth at the beginning of the ninth month, in the eighth month, in the seventh month or worse in the sixth month it is an early birth The gestational period in which delivery takes place plays a fundamental role in the well-being of the newborn. The causes of preterm labor are many and some may be concomitant. Generally the causes of premature birth can be found in three macro-categories:

  • Maternal causes;

  • Fetal causes;

  • Placental causes.

Premature birth due to maternal causes

The pathologies that represent a risk of premature birth are represented both by factors that purely concern the female reproductive system and by systemic pathologies of the mother that have a negative impact on the course of pregnancy. Among the maternal causes are:

  • Uterine malformations;

  • Cervical incontinence;

  • Cervico-vaginal infections;

  • Cholestasis of pregnancy;

  • Hypertension;

  • Pre eclampsia and eclampsia;

  • Severe underweight;

  • Stress;

  • Age (less than 20 years and over 38 years);

  • Physical injury or trauma;

Fetal causes of preterm labor

Preterm birth can originate from causes that affect the fetus (s) and its well-being such as:

  • Monochorionic and monoamniotic twin pregnancies in which the fetuses are in a single amniotic sac and are fed by a single placenta. In these cases, delivery must take place no later than 35 weeks.

  • Bi-chorionic and biamniotic twin pregnancies in which the fetuses are in two different amniotic sacs and are each fed by a placenta. In these cases, the guidelines recommend that delivery be completed no later than 37 weeks of pregnancy.

  • Fetal stunting in which the fetus stops growing and shows signs of distress.

Placental causes of premature birth

The placental causes of premature birth concern pathologies and functional alterations of the placenta such as:

  • Placenta previa;

  • Placental malformations;

  • Premature rupture of membranes;

  • Excess of amniotic fluid, polyhydramnios;

  • Detachment of placenta.

However, it must be said that there are other causes of preterm birth in which serious maternal or fetal conditions suggest that it is appropriate to carry out the birth quickly. In the event that a risk of preterm birth is suspected, it is advisable to go to a suitable facility equipped with neonatal intensive care in order to ensure adequate support for the newborn.

Signs and symptoms of premature birth

It is important to know the symptoms associated with preterm birth so that you can go to the hospital right away. The goal is to counteract premature labor so that it does not get to a point where it does not respond to any treatment. Periodic checks during pregnancy are used to verify that the uterine cervix does not undergo changes. Signs of a threat of premature birth:

  • Uterine contractions occurring less than or equal to 10 minutes with or without pain.

  • Moderate cramps similar to menstrual pain perceived in the lower abdomen.

  • Constant or intermittent feeling of weight down.

  • Rupture of the membranes.

  • Back pain: dull, constant or intermittent pain even of low intensity in the back

  • Loss of mucous plug and abundant pinkish vaginal discharge

  • Abdominal cramps with or without diarrhea.

If these symptoms are present, it is advisable to go to the nearest hospital in order to intervene quickly.

  • The risk of premature birth may require:

  • Hospitalization.

  • Absolute rest.

  • Hydration with intravenous infusions.

  • Blood chemistry tests.

  • Vaginal culture and urine culture in order to detect any infections that may have triggered contractile activity.

  • Drug therapy which consists of the administration of drugs to try to suppress uterine contractions.

  • Cervical cerclage

If the threat has disappeared and there are no dangers for the mother and the fetus, discharge and return home requires the implementation of measures that minimize the risk that the threat of premature birth is repeated.

Avoid Preterm Birth: Preventing Premature Birth

There are behaviors that help reduce the risk of premature birth represented by:

  • Rest for a long time at least two or three times a day lying on the left side;

  • Take 2-3 liters of water per day;

  • Avoid caffeinated sodas and carbonated soft drinks;

  • Empty your bladder at least every 2 hours while awake;

  • Avoid lifting heavy objects and if there are small children in the house, avoid picking them up;

  • Avoid stimulation of the nipples and breasts;

  • Reduce or eliminate sexual activity.

After a threat of preterm birth the lifestyle of pregnancy changes. In order not to get too bored, carry out pleasant activities even at rest such as reading, doing small manual jobs, trying to focus on one day or one week at a time rather than on longer periods of time. If it is necessary to remain at rest, equip a room such as the living room where you do not remain isolated for too long.

Therapy for the threat of premature birth

Therapy to counteract the risk of premature birth essentially depends on the cause. Therapies to counter the threat of premature birth are:

  • Cervicometry;

  • Tocolytic drugs;

  • Progesterone;

  • Cerclage;

  • Pressario;

  • Magnesium sulfate;

  • Antibiotics.


Cervicometry is the ultrasound measurement of the length of the cervical canal.

A shortening of the cervix is ​​a sign that the cervix is ​​changing with the risk of labor being triggered. The length of the cervical canal is a good predictor of the risk of premature birth but should not be taken as an isolated indicator. The guidelines recommend undergoing cervicometry during the 2nd trimester of pregnancy between the 18th and 24th week of pregnancy. In these cases, the measurement of the cervix represents a screening to identify cases of shortened cervix early.

Tocolytic drugs

If a diagnosis is made of a threat of preterm birth caused by an excess of uterine contractility that determines the shortening and premature maturation of the cervix, drugs are administered to try to block uterine contractions. The decision of which drug to use depends on the gestational age of the fetus, the presence of maternal pathologies and the side effects. The tocolytic drugs used to try to counteract the risk of premature birth are:

  • Indomethacin: prostaglandin synthesis inhibitors

  • Nifedipine: calcium channel blockers

  • Ritodrine, Terbutaline: Beta-sympathomimetics

  • Atosiban: oxytocin antagonists

  • Magnesium sulfate

Indomethacin inhibits the synthesis of prostaglandins responsible for contractions of the myometrium, that is, the muscular part of the uterus. Prostaglandin synthesis inhibitors are among the most successful drugs for countering premature labor but with potential side effects, therefore, their use is not recommended after the thirty-second week. Nifedipine is a vasodilator that inhibits the passage of calcium inside the membranes by inhibiting their contraction. Calcium antagonists are contraindicated in the case of cardiac pathology and hypotension of the mother. Atosiban, known by the name of Tractocile, is the drug most used in the threat of premature birth as it presents fewer risks for both mother and fetus. According to the latest Sigo guidelines, tocolytic drugs can be administered by 34.6 weeks of pregnancy.


Progesterone inhibits prostaglandins which are responsible for cervical ripening and changes in the cervix. Generally, progesterone is used in women who have had a previous history of premature birth due to early changes in the cervix. Progesterone can be administered intramuscularly, orally or vaginally.

Cervical cerclage

Cervical cerclage is a surgical procedure that serves to correct and prevent cervical insufficiency. Cervical incontinence causes an early opening of the cervix which seriously endangers the continuation of the pregnancy. With cerclage, the cervix is ​​held tight by a special tape that will be removed at the end of pregnancy. The recommended gestational period for cervical cerclage is between the 16th and 24th week.


The pressarium is an invasive vaginal device that can be used in women with a shortened cervix between 18 and 22 weeks of pregnancy. The device would act by changing the angle between the cervix and uterus, thus decreasing both the pressure on the cervix and the contact between the membranes and the vaginal bacteria. There are several types of pessary: ​​most of the more recent studies have used the Arabin1 pessary. The use of the pessary as a prophylaxis of preterm birth can be promising, but the evidence is in progress.

Magnesium sulfate

Magnesium sulfate is a drug used both in the treatment of pre-eclampsia and as a tocolytic. The drug gives good results but can only be used for short periods as long-term treatment could cause demineralization of the fetal bones. Recent studies have shown that the use of magnesium sulfate before the 32nd week of pregnancy has a fetal neuro-protective effect as it reduces the risk of cerebral palsy if the baby is born prematurely. What is the optimal treatment is yet to be clarified


Antibiotic therapy is given in cases of preterm rupture of the membranes where the goal is to keep the pregnancy as long as possible. The use of antibiotics reduces the risk of infections for both the woman and the fetus and reduces fetal morbidity related to prematurity. The guidelines recommend a high dosage of antibiotics and, if necessary, also the combination of multiple antibiotics such as ampicillin and macrolides.

Pulmonary maturation of the fetus with corticosteroids

In cases where there is a threat of premature birth, the pulmonary maturation of the fetus is stimulated by administering cortisone to the mother. Prophylaxis is performed by administering intramuscularly:

  • two 12-milligram doses of betamethasone one day apart or, alternatively,

  • 4 doses of 6 milligram dexamethasone always intramuscularly, but 12 hours apart.

Antenatal corticosteroid prophylaxis is effective in reducing perinatal mortality and morbidity in women at risk of preterm delivery between 24 and 34 gestational weeks, 24 hours to 7 days after dosing.

 premature newborn
premature newborn

At how many weeks the fetus is most likely to survive

The incidence of preterm births is around 12% and the risk for the newborn is represented by the degree of immaturity resulting from the gestation period which, if too early, can lead to the death of the fetus. Due to immaturity, premature babies are not adequately equipped to live a life outside the uterus, therefore, they need to be transferred to a neonatal intensive care unit where the uterine environment is recreated in thermo-cots. With the help of modern technologies, babies born even 10-12 weeks before term survive.


pocket obstetrics and gynecology



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