Guidelines for Symphysis‑Fundal Height (SFH) Measurement and Surveillance

Measurement Protocol

Proper technique requires measuring from the uterine fundus (variable point) to the symphysis pubis (fixed point) while concealing the tape to reduce observer bias, which minimizes intra‑ and inter‑observer variation. 2
Serial SFH measurements should be performed at every antenatal appointment after 24 weeks, but no more frequently than every 2 weeks; the first measurement must be taken between 26 + 0 and 28 + 6 weeks’ gestation. 1

Routine SFH surveillance should commence between 26 + 0 and 28 + 6 weeks, with the initial measurement completed by 28 + 6 weeks. 3
Performing measurements between 24 + 0 and 26 + 7 weeks generates excessive false‑positive referrals because centile relationships are unstable at earlier gestations. 2
Serial (repeated) SFH measurements improve predictive accuracy for fetal growth abnormalities compared with a single assessment. 2

An ultrasound assessment is indicated if a single SFH reading plots below the 10th centile or if two measurements taken more than 2 weeks apart show no increase in SFH. 3
The urgency of ultrasound referral should be modulated by additional clinical findings such as reduced fetal movements or abnormal maternal blood pressure. 3
In large cohort studies, SFH has an overall sensitivity of approximately 47 % for detecting small‑for‑gestational‑age (SGA) fetuses. Specificity is high (≈ 98 %), and SFH performs better than abdominal palpation alone, although sensitivity varies from 19 % to 53 % depending on population risk. 1

Routine SFH measurement is unreliable in women with a body‑mass index ≥ 35 kg/m² at booking; such patients should be monitored with alternative methods (e.g., direct ultrasound). 2
Additional conditions that markedly limit SFH accuracy include:
- Large uterine fibroids (clinical judgment at booking) 3
- Abnormal fetal lie (transverse or oblique presentation) 1
- Polyhydramnios of any etiology 3
- Fetal head engagement in the pelvis 2
All pregnant women should be assessed at booking for the above conditions to decide whether SFH surveillance is appropriate or whether direct ultrasound should be employed. 2

Providers must select an appropriate SFH chart (standard, population‑based, or customized) and ensure that staff are trained in its application. 3
The INTERGROWTH‑21st SFH standards (2015) were developed with robust methodology and can be integrated into electronic health records, although validation in heterogeneous populations remains limited. 3
Customized charts that adjust for maternal characteristics have been associated with improved SGA detection rates (29 %–48 %), but the benefit is confounded by concurrent comprehensive training programs. 3
No randomized trials have compared different chart types for perinatal outcomes. 3

Despite limited sensitivity for SGA detection, SFH remains a reasonable first‑level screening tool for low‑risk pregnancies because it is easy to perform, requires minimal resources, and carries essentially no adverse effects. 2
In resource‑limited environments where universal ultrasound surveillance is not feasible, SFH measurement enables selective referral for ultrasound, optimizing the use of limited imaging resources. 2