Preterm Labor Causes, Signs, Risks, and Precautions

Many pregnancies last the full term of thirty-seven weeks. However, there are times when babies arrive after the twentieth week but before the 37th week of pregnancy; thus called premature or preterm baby.

If you are pregnant and would like to learn more about preterm labor causes, signs, risks, and precautions, then you have come to the right place.

Preterm Labor Causes

In most instances, doctors do not know the exact cause, but they can point to several risk factors that could trigger an early delivery. These include:

Pregnancies occurring at shorter intervals in between: You are at a greater risk of having a preterm birth if you became pregnant much sooner than eighteen months after conceiving your last child [1].

Smoking, drug, and alcohol use: These teratogens will increase your risk of having a miscarriage, as well as having a baby that is born too early or with low birth weight [2].

Vaginal and uterine infections: A majority of preterm births happen because of infections in the genital tract and uterus. According to the experts, these infections cause inflammation that triggers the release of prostaglandins, which is the substance that induces labor when a pregnancy is full-term [3].

Pregnancy complications: You are more likely to have a preterm delivery if you have certain complications, such as excessive amniotic fluid, preeclampsia, and gestational diabetes, in addition to placenta problems such as placental abruption or previa.

Structural anomalies in the uterus/cervix: It will be more difficult for you to carry your baby to full term if your uterus is very large, malformed, or has any other structural abnormality. The same thing can happen with cervix problems [4].

Stress levels: Severe emotional stress that is trauma-related can trigger the release of hormones and in turn cause labor contractions [5].

Multiple pregnancies: You are more likely to have multiples coming earlier than a single baby [6].

Past preterm birth: Your risk will increase if you have previously had a premature delivery [7].

Gum infections: Pregnant women are more susceptible to periodontal disease, and this, in turn, can lead to preterm labor. It is believed that the bacterium which causes gum inflammation can get into the pregnant woman’s bloodstream and reach the fetus, thereby triggering an early delivery [8].

Getting pregnant before the age of seventeen or after thirty-five: During these years, you have a greater chance of delivering prematurely.

Occupational factors: Jobs that are extremely stressful physically or ones that require lots of heavy physical work have been linked to premature labor.

Other factors that could put you at risk of delivering your baby early include past abortions or miscarriages, stressful life events such as domestic violence or the death of a loved one, being extremely underweight or overweight before pregnancy, physical trauma or injury, and not getting the necessary prenatal care from a healthcare professional.

Signs of Preterm Labor

Regular contractions: These are contractions which occur every ten minutes or more and do not subside even if you change positions.

You should not confuse them with Braxton Hicks contractions, which are practice contractions, irregular, and no cause for concern. Be sure to call your doctor immediately if you are not sure.

Change in your vaginal discharge: You should look out for any blood-streaked vaginal discharge, or vaginal bleeding, including light bleeding.

Flu-like symptoms: This includes nausea, diarrhea, or vomiting. You should call your medical doctor even if you are having a mild case or if you cannot tolerate liquids/fluids for over eight hours.

Vaginal leaking fluid: This could be a sign that your water is broken. To be certain, you could do a sniff test to see if it has an ammonia smell to it. If it does not, then what you are seeing might be amniotic fluid.

Back pain: This could be a dull back pain in the lower area. The pain might come and go or occur constantly but will not ease even if you change positions to get comfortable.

Cramps: These will be menstrual-like cramps or strong cramps in the lower abdomen or back. They can also feel similar to gas pains which might be accompanied by diarrhea.

Increased pressure on the pelvic area: Contact your doctor if you are feeling a significant amount of pressure in the pelvic area.

Preterm Labor Precautions

There is no sure way of preventing preterm or premature labor, but the following are some of the things you can do to avoid it:

  • Stay hydrated
  • Infections, such as yeast or bacterial vaginosis, should be checked and treated as early as possible
  • Keep your regular prenatal appointments with your midwife or doctor

In conclusion, you should know that you could experience all or some of the symptoms above and not go into labor.

This means that you cannot be too cautious when you are pregnant, so all of the possible warning signs should be considered. You will be able to seek treatment early if you recognize the labor signs sooner.


  1. LANG JM, LIEBERMAN E, RYAN KJ, MONSON RR. Interpregnancy interval and risk of preterm labor. American Journal of Epidemiology. 1990 Aug 1;132(2):304-9.
  2. Kyrklund‐Blomberg NB, Granath F, Cnattingius S. Maternal smoking and causes of very preterm birth. Acta obstetricia et gynecologica Scandinavica. 2005 Jun;84(6):572-7.
  3. Yoon BH, Romero R, Park JY, Oh KJ, Lee J, Conde-Agudelo A, Hong JS. Antibiotic administration can eradicate intra-amniotic infection or inflammation in a subset of patients with preterm labor and intact membranes. American journal of obstetrics and gynecology. 2019 Mar 27.
  4. Lekovich J, Stewart J, Anderson S, Niemasik E, Pereira N, Chasen S. Placental malperfusion as a possible mechanism of preterm birth in patients with Müllerian anomalies. Journal of perinatal medicine. 2017 Jan 1;45(1):45-9.
  5. García-Blanco A, Diago V, De La Cruz VS, Hervás D, Cháfer-Pericás C, Vento M. Can stress biomarkers predict preterm birth in women with threatened preterm labor?. Psychoneuroendocrinology. 2017 Sep 1;83:19-24.
  6. Fuchs F, Senat MV. Multiple gestations and preterm birth. InSeminars in Fetal and Neonatal Medicine 2016 Apr 1 (Vol. 21, No. 2, pp. 113-120). WB Saunders.
  7. Sentilhes L, Sénat MV, Ancel PY, Azria E, Benoist G, Blanc J, Brabant G, Bretelle F, Brun S, Doret M, Ducroux-Schouwey C. Prevention of spontaneous preterm birth: Guidelines for clinical practice from the French College of Gynaecologists and Obstetricians (CNGOF). European Journal of Obstetrics & Gynecology and Reproductive Biology. 2017 Mar 1;210:217-24.
  8. Dasanayake AP, Naftolin F. The association between periodontitis and preterm labor (PTL). InA clinician’s guide to systemic effects of periodontal diseases 2016 (pp. 67-79). Springer, Berlin, Heidelberg.
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