Prevention of spontaneous preterm delivery – an update on where we are today

Figures & data

Figure 1. Estimated global rate of the rates of preterm birth in 2014. (Courtesy of Chawanpaiboon et al. Lancet 2019) [4].

Table 1. Effectiveness of interventions in primary prevention (data are presented as the OR changes with each factor).

Risk Factor	How great is the risk?
Pregnancy in adolescents	Increased prevalence of anemia, PIH, LBW prematurity, FGR and neonatal mortality
Birth spacing
Short interval (<6 months) Long interval (>24 months)	PTB OR-1.45, LBW OR-1.65 PTB OR-1.21, LBW OR-1.37
Pre-pregnancy weight status
Underweight Overweight and obese	PTB OR-1.32, LBW OR-1.64PTB OR-1.07. Maternal overweight is a risk factor for many pregnancy complications such as LBW, GDM, Congenital malformations (that may themselves lead to PTB)
Micronutrients deficiency
Folate Iron	Folate deficiency linked to neural tube defects Anemia increases risk of PTB and LBW
Chronic illness
Diabetes mellitus Hypertension Anemia	Increased risk of SB, PNM, Congenital malformations, PTB, PIH/PET LBW
Poor mental health and intimate partner violence	Increased risk of PTB, LBW, depression during pregnancy and after birth
Infectious diseases such as HIV/AIDS, STIs, Rubella, syphilis etc.	Spontaneous miscarriages, congenital malformations and PTB
Smoking and recreational drug use	PTB OR-2.2 Increased risk of miscarriage, placental disorders, congenital malformations LBW

OR: Odds ratio; PTB: preterm birth; LBW: low birth weight; PIH: pregnancy-induced hypertension; PET: pre-eclampsia; PNM: perinatal mortality; SB: stillbirth; STI: sexually transmitted infection, HIV/AIDS: human immunodeficiency virus/Acquired immune deficiency.

Table 2. Accuracy of various biomarkers for the diagnosis of PTL.

Biomarker (Test)	Sensitivity	Specificity	Positive predictive value (PPV)	Negative predictive value (NPV)
ofFN	65	97	38–50	92–99
IGFBP-1	70	90–100	50	91–96
IL-6	76	79	65	87
IL-8	62	74	53	80
CRH	50	88	85	–
ACTH	68	88	88	–
CRP	54	81	74	64
Estriol	71	77	–	–
S Relaxin	27	96	78	72

Figure 2. Transvaginal ultrasound scan demonstrating an intra-amniotic sludge above the internal cervical os (A and B - sludge of different sizes).

Figure 3. Placement of balloon to reduce membranes prior to cerclage insertion with Uniconcave catheter (Courtesy of Lv et al. 2000) [77].

Chawanpaiboon S, Vogel JP, Moller A-B, et al. Global, regional, and national estimates of levels of preterm birth in 2014: a systematic review and modelling analysis. Lancet Glob Health. 2019;7(1):e37–e46.

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Chatzakis C, Efthymiou A, Sotiriadis A, et al. Emergency cerclage in singleton pregnancies with painless cervical dilatation: a meta-analysis. Acta Obstet Gynecol Scand. 2020;99(11):1444–1457.

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