Hearing the words preterm birth can make everything speed up—scans, monitoring, decisions—while your mind stays stuck on one thought: “Is my baby safe?” A preterm birth means birth before 37 completed weeks. A few days can change lung maturity, feeding readiness, and temperature control, so doctors follow clear steps to judge risk, buy time when it is safe, and prepare newborn care. Also worth saying plainly: preterm birth is common and usually multifactorial, not a personal fault.

What “preterm” means (and why days matter)

In obstetrics, completed weeks count. 36 weeks + 6 days is still preterm, 37 weeks + 0 days is term.

Organs still maturing late in pregnancy:

• Lungs (surfactant increases)
• Brain (rapid growth and wiring)
• Gut (feeding coordination)
• Temperature regulation (less body fat = more heat loss)
• Immunity (higher infection susceptibility)

You may hear “premature” in everyday talk. Clinically, “preterm” is the precise term for timing.

Preterm birth, low birth weight, and SGA: different labels

• Preterm birth = when baby is born.
• Low birth weight = often <2,500 g, at term or preterm.
• Small for gestational age (SGA) = weight lower than expected for the pregnancy weeks (often <10th percentile).

A baby can be preterm but not SGA, or SGA at term. Doctors separate these because feeding and monitoring needs differ.

Pregnancy dating: why the due date may shift

Dating from the last menstrual period (LMP) can be off if cycles vary. A first-trimester ultrasound (before 14 weeks) using crown–rump length is usually accurate within 5–7 days. If LMP and early scan differ by more than about a week, clinicians generally rely on ultrasound dating—this affects timing of steroids, referral decisions, and neonatal preparation.

Gestational age categories of preterm birth

Clinicians group preterm birth by weeks:

• Extremely preterm: <28 weeks
• Very preterm: 28 to <32 weeks
• Moderate preterm: 32 to <34 weeks
• Late preterm: 34 to <37 weeks

Late preterm is most common. Earlier births more often need longer NICU care.

Threatened preterm labour: why it feels confusing

Threatened preterm labour is considered when there are:

• regular, persistent uterine contractions, and/or
• signs the cervix is changing (shortening, effacing, opening).

A “tight belly” can also happen with dehydration, fatigue, or a urinary tract infection (UTI). The key clinical point is whether the cervix is changing.

Pathways to preterm birth (spontaneous, indicated, PPROM)

• Spontaneous preterm birth: labour starts on its own, or membranes break before labour.
• Medically indicated preterm delivery: doctors advise early delivery because continuing pregnancy is riskier (for example severe preeclampsia, fetal distress, severe growth restriction, major placental complications).

PPROM (waters breaking early)

PPROM is rupture of membranes before labour and before 37 weeks, a common route to preterm birth. Concerns include infection and cord problems, and the balance between safely prolonging pregnancy and delivering when needed.

How common preterm birth is (and why it matters)

Globally, preterm birth affects about 10% of births, and the burden is high in South Asia too. For families, it may mean hospital stays, travel between home and NICU, pumping schedules, and emotional strain. Many babies do very well, some need closer follow-up for growth, breathing, vision/hearing, and development.

Why preterm birth can happen

Often, more than one factor is involved:

Infection and inflammation

Infections can irritate uterus and membranes and increase inflammatory signals.

• UTIs matter even if symptoms are mild.
• Vaginal infection and intra-amniotic infection (chorioamnionitis) can weaken membranes and trigger contractions.

Cervical factors (short cervix, cervical insufficiency)

A short cervix in mid-pregnancy increases risk of spontaneous preterm birth. Depending on history and findings, options may include vaginal progesterone or, in selected cases, cervical cerclage.

Placental problems

• Placenta previa can cause bleeding.
• Placental abruption can be urgent.
• Placental insufficiency can reduce oxygen and nutrients and contribute to fetal growth restriction.

Hypertension and preeclampsia

Preeclampsia can worsen quickly and affect organs and placental function. If severe, early delivery may be safer.

Multiple pregnancy

Twins and higher-order pregnancies carry a higher chance of preterm birth.

Modifiable contributors (without blame)

Smoking/second-hand smoke, alcohol/non-prescribed drugs, dehydration, heavy physical strain, severe fatigue, chronic stress with barriers to care, and short gaps between pregnancies can contribute, but they do not explain every case.

Signs of preterm labour: when to seek care

Call your doctor/maternity unit if under 37 weeks and you have:

• four or more contractions in an hour, especially if regular
• pelvic pressure, constant dull back pain
• period-like cramps (sometimes with loose motions)
• watery/bloody/mucus-like discharge, or much more discharge

Seek urgent evaluation for:

• a gush or continuous trickle of fluid
• any vaginal bleeding
• clearly decreased fetal movement

While calling: time contractions, note fever or burning urine, drink water, rest on your side. Strict bed rest is not proven to prevent preterm birth and can increase clot risk.

In-hospital evaluation: how risk is assessed

Teams may do the following.

• check vitals and examine symptoms
• monitor baby’s heart rate and contractions (CTG)
• assess cervix, and sometimes do a transvaginal scan for cervical length (a common “short” threshold is <=25 mm)

Some centres use fetal fibronectin (fFN) in selected symptomatic cases: a negative result is reassuring for low short-term birth risk, a positive result needs context.

Urine tests, swabs, blood tests, and ultrasound (growth, amniotic fluid, sometimes Dopplers) may be done.

When preterm birth seems likely: treatments

The goal is often to gain 24–48 hours safely for medicines to work and for referral if needed.

• Tocolysis: medicines to reduce contractions briefly in selected cases (often before 34 weeks).
• Antenatal corticosteroids: commonly used when delivery within 7 days is likely (often 24–34 weeks) to support lung maturity.
• Magnesium sulfate: may be offered for fetal neuroprotection when birth before 32 weeks is expected.
• Antibiotics: used for suspected infection, often used with PPROM, and sometimes during labour for Group B Strep prevention depending on protocols.

Delivery may be advised if there is severe preeclampsia, major bleeding/abruption, serious infection, fetal distress, or severe growth restriction.

If advanced neonatal support is needed, in-utero transfer to a higher-level unit is preferred when safe.

Immediate care after preterm birth

Common priorities in NICU:

• breathing support (often CPAP, sometimes surfactant/ventilation)
• warmth (radiant warmer/incubator, kangaroo mother care when safe)
• feeding support (human milk preferred, tube feeds and sometimes fortification for very preterm babies)
• infection prevention and developmental care (sleep protection, gentle handling, pain relief when needed)

Parents are encouraged to participate in care as soon as baby is stable—skin-to-skin, comforting, and feeding support.

Short-term complications linked with prematurity

Depending on gestational age, babies may face:

• respiratory distress and apnoea of prematurity
• brain bleeding such as intraventricular haemorrhage (IVH)
• gut disease such as necrotising enterocolitis (NEC)
• eye condition retinopathy of prematurity (ROP)
• infections and jaundice (may need phototherapy)

Long-term outcomes and follow-up

Many children do very well after preterm birth. Follow-up often uses corrected age (adjusting for weeks early) for growth and milestones, especially in the first 2 years.

Some children benefit from early therapies (physio, occupational therapy, speech). Very preterm infants may have ongoing lung concerns like bronchopulmonary dysplasia (BPD). Vision and hearing screening are part of standard care.

Key takeaways

• Preterm birth means birth before 37 completed weeks, timing affects lung, brain, and feeding maturity.
• Threatened preterm labour involves contractions and/or cervical change, persistent symptoms deserve assessment.
• Causes of preterm birth can include infection/inflammation, PPROM, placental problems, hypertension/preeclampsia, growth restriction, multiple pregnancy, and short cervix.
• Warning signs (regular contractions, pressure, bleeding, leaking fluid, decreased movements) should prompt urgent advice.
• Hospital care may include CTG, cervical length, fFN in selected cases, and infection checks.
• If preterm birth seems likely, doctors may aim to safely gain 24–48 hours for key medicines and transfer when needed.
• After birth, NICU care focuses on breathing, warmth, feeding (human milk), infection prevention, and developmental care—with parents involved.
• Support is available through your obstetrician and neonatology team, you can also download the Heloa app for personalised guidance and free child health questionnaires.

Further reading:

• Preterm birth (https://www.who.int/news-room/fact-sheets/detail/preterm-birth)
• Preterm Birth | Maternal Infant Health (https://www.cdc.gov/maternal-infant-health/preterm-birth/index.html)
• Premature birth – Symptoms and causes (https://www.mayoclinic.org/diseases-conditions/premature-birth/symptoms-causes/syc-20376730)