How is premature birth defined?

Written by Zhang Lu
Obstetrics
Updated on May 24, 2025
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Preterm birth is defined in relation to miscarriage and full-term birth. A birth before 28 weeks of pregnancy is considered a miscarriage; a birth after 37 weeks of pregnancy is considered full-term; and a birth between 28 weeks and 36 weeks and six days is considered preterm. Since preterm birth occurs in the late stages of pregnancy, the fetus has a certain chance of survival. However, efforts should be made to delay the timing of preterm birth as much as possible to increase the survival rate of the fetus. It is generally believed that births between 28 and 34 weeks are considered early preterm, during which the survival probability of the fetus is relatively low; whereas births after 34 weeks up to 36 weeks and six days are considered late preterm, during which the maturity of the fetus is higher and the survival rate is also relatively high.

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Written by Du Rui Xia
Obstetrics
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How to care for premature infants

The care of premature babies is very important. Since the physical resistance of premature babies is weaker than that of full-term infants, premature babies generally need to be placed in incubators to maintain body temperature. If an incubator is not available, methods such as using a hot water bottle for warmth can be employed, or putting cotton hats on the babies. During feeding, breastfeeding is an option. For very small babies who have poor sucking ability or uncoordinated swallowing functions, or for babies who are ill, the mother can express her milk, which can then be fed to the baby via a tube through the nose. Artificial feeding is also an option.

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Written by Du Rui Xia
Obstetrics
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Can premature birth be natural delivery?

Whether a vaginal delivery is possible in the case of preterm labor depends on the condition of the pregnant woman and the fetus, including the woman's birth canal, labor strength, the size and position of the fetus, among other factors. Generally, during a medical visit, a doctor will measure the woman's pelvis to roughly determine whether vaginal delivery is feasible. Women who experience preterm labor should go to the hospital for timely medical care and choose a hospital equipped for emergency services. If preterm delivery occurs, the baby's respiratory function may be relatively weak, necessitating the use of special equipment to assist breathing.

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Written by Liu Wen Li
Obstetrics
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Are the twins premature?

The likelihood of premature birth is higher in twins than in singletons, but this does not mean that all twins will be born prematurely. In the case of twins, there are two children in the uterus. Generally, the combined weight of two children is more than that of one. Additionally, there might be more amniotic fluid and a larger placental area. Therefore, the contents of the uterus occupy more volume, and when the uterus is stretched to a certain extent, its sensitivity increases. As a result, some may experience contractions and give birth prematurely before reaching 37 weeks of pregnancy.

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Written by Zhang Lu
Obstetrics
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Will early engagement of the fetus lead to premature birth?

Fetal engagement refers to the leading part of the fetus having entered into the woman's pelvis. There isn't a necessary correlation between fetal engagement and preterm birth; however, fetal engagement could indicate a possibility of preterm birth or an upcoming labor. It is important to pay attention to the timing of fetal engagement and the expectant mother's sensations post-engagement. Firstly, for the vast majority of pregnant women, fetal engagement should occur after week 32 or 34. Early engagement should prompt attention to the presence of other clinical symptoms. Secondly, be mindful if there are feelings of descent or abdominal pain after the fetal engagement. Regular checks of the cervical canal length should be conducted if these sensations frequently occur. If the cervical canal is progressively shortening, it may suggest a risk of preterm birth. If there is no shortening of the cervical canal, it means that the fetal engagement and these clinical symptoms are unlikely to cause preterm birth.

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Written by Zhao Li Li
Obstetrics
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Signs of premature birth

Generally, babies born between 28 and 37 weeks of gestation are considered premature. Normally, premature babies have underdeveloped organ systems, which makes them prone to serious abnormalities in various organs after birth. This can lead to conditions such as respiratory distress syndrome or cerebral palsy. Signs of premature labor typically include sudden regular abdominal pain without any other abnormalities, accompanied by clear uterine contractions and a feeling of abdominal heaviness, with a persistent, notable dilation of the cervix.