How is preterm birth defined?

Written by Liu Wen Li

Obstetrics

Updated on February 25, 2025

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Premature birth means that the gestational period is not yet complete, and the baby is born before reaching full term, which is called preterm birth. Specifically, this ranges from more than 28 weeks but less than 37 weeks of gestation. Due to the incomplete development of premature infants, their organ functions are relatively poor. Therefore, caring for premature infants can be more challenging, often requiring pediatric care and enhanced nursing. Moreover, there are more complications, so it is important to try to prevent premature births as much as possible.

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Written by Zhang Lu

Obstetrics

1min 7sec

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Is excessive amniotic fluid likely to cause premature birth?

Polyhydramnios is relatively common during pregnancy and can have a certain impact on the fetus. There are many reasons that can cause polyhydramnios, but regardless of the cause, polyhydramnios tends to lead to preterm birth. When there is an excessive amount of amniotic fluid, it puts significant pressure on the amniotic sac, which can easily lead to premature rupture of membranes. Premature rupture of membranes itself can stimulate the cervix, release inflammatory mediators, thereby causing contractions and symptoms of preterm labor. After the membranes rupture prematurely, infection within the uterine cavity is likely to occur, generally meaning that the possibility of keeping the pregnancy going for a long duration is unlikely. Therefore, polyhydramnios is associated with a higher risk of preterm labor. In clinical practice, if excessive amniotic fluid is detected during prenatal check-ups, it is advised to control the diet, engage in appropriate physical activities, or use other methods to keep the amniotic fluid level within the normal range.

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Written by Du Rui Xia

Obstetrics

55sec

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Causes of Premature Birth

There are many causes of preterm birth, such as cervical loosening during pregnancy, gynecological inflammations, underdeveloped uterus, congenital uterine malformations, and uterine fibroids, as well as pregnancy-related hypertension and diabetes, which can also lead to preterm labor. Additionally, carrying twins can increase uterine tension and potentially cause preterm birth. Other factors include long-distance travel, fatigue, emotional fluctuations, family relocation, abdominal trauma, prolonged standing, high psychological stress, advanced maternal age, and placental abruption during pregnancy, all of which can contribute to the occurrence of preterm birth.

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Written by Du Rui Xia

Obstetrics

49sec

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How many weeks early can a premature baby survive?

Preterm birth refers to births that occur after 28 weeks of pregnancy but before 37 weeks. Preterm infants have lower resistance compared to full-term infants and generally require special care to survive. The survival rate varies with the gestational age: at 32 to 33 weeks, the survival rate can reach 95%; at 28 to 31 weeks, it is between 90% and 95%; at 26 weeks, it is around 80%; and at 27 weeks, it is about 90%. After 34 weeks of pregnancy, the survival rate of the baby is very high, almost the same as that of a full-term baby.

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Written by Zhang Lu

Obstetrics

59sec

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Premature birth is what it means.

Preterm birth refers to giving birth before full-term pregnancy, defined as delivery occurring between 28 and 36 weeks plus 6 days of gestation. Corresponding conditions are miscarriage and full-term delivery: before 28 weeks is termed a miscarriage, while delivery after 37 weeks is termed full-term birth. Because preterm infants already possess certain vital functions, most can survive with appropriate emergency intervention and treatment. However, the risks associated with preterm birth are relatively high and depend on the specific causes of prematurity. Some premature births are due to premature rupture of membranes, while others are medically induced, for example in cases of abruptio placentae or severe preeclampsia. Therefore, it is crucial in clinical practice to provide rational treatment for preterm labor, aiming to extend the duration of pregnancy as much as possible to avoid neonatal death.

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Written by Zhao Li Li

Obstetrics

47sec

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Is it normal for a premature baby to weigh more than five jin?

If the newborn is currently premature and weighs a bit over five jin (approximately 2.5 kilograms), it is generally considered within the normal range. Typically, if a newborn weighs more than 2500 grams, it is considered a full-term birth weight and there are no abnormalities. Therefore, if the newborn's weight is within the normal range after birth and there are no abnormalities in the development of the organs, it is possible to observe temporarily without the need for an incubator. It is also crucial to closely monitor the various vital signs of the newborn and pay attention to normal feeding and care.