Illustration of a newborn baby's face with highlights on key facial features.

Unlocking Newborn Health: Understanding Palpebral Fissure and Lip Measurements

Samir D’Costa in Health & Wellness December 2025 • 4 min read.

"A comprehensive guide to interpreting newborn facial measurements and their significance for early health assessments."

Every newborn undergoes a thorough physical examination to ensure they're healthy and developing as expected. While many factors are considered, specific measurements, such as those of the eyes and lips, play a crucial role in identifying potential underlying issues. These seemingly small details can provide valuable clues to a baby's overall well-being.

Researchers Maria dos Anjos Mesquita and Conceição Aparecida de Mattos Segre conducted a study focused on these key facial measurements. Their work, centered in a public maternity ward in São Paulo, Brazil, aimed to establish standard measurement curves for the palpebral fissure (the length of the eye opening) and the vermilion border of the upper lip (the red portion).

Why are these measurements so important? They can serve as indicators of facial dysmorphism, or differences in facial features, which may be associated with certain syndromes or developmental conditions. By establishing typical measurement ranges, healthcare professionals can more easily identify newborns who may require further evaluation.

Palpebral Fissure and Vermilion Border: What Do These Measurements Tell Us?

Illustration of a newborn baby's face with highlights on key facial features.

The palpebral fissure is simply the opening between the eyelids. Its length is measured from the inner corner (endocanthion) to the outer corner (exocanthion) of the eye. The vermilion border, on the other hand, refers to the exposed red part of the upper lip. Measuring its width provides another key data point.

In their study, Mesquita and Segre measured these features in 1,964 newborns with gestational ages ranging from 25 to 43 weeks. The measurements were taken within the first 24 to 72 hours of life to avoid any influence from swelling related to labor and delivery. Here's what they found:

Palpebral Fissure: The average measurement was 1.98 cm, with a range of 0.80 to 3.00 cm.
Vermilion Border: The average width was 0.51 cm, ranging from 0.20 to 0.90 cm.

Based on this data, the researchers created percentile curves, which illustrate the distribution of these measurements across different gestational ages. These curves serve as a reference for healthcare providers to assess whether a newborn's measurements fall within the expected range.

Why This Research Matters: Early Detection and Intervention

The establishment of these percentile curves provides a valuable tool for healthcare professionals. By comparing a newborn's facial measurements to these standards, clinicians can identify potential dysmorphic features that may warrant further investigation. Early detection is crucial, as it allows for timely intervention and support for children who may have underlying health conditions.

About this Article -

This article was crafted using a human-AI hybrid and collaborative approach. AI assisted our team with initial drafting, research insights, identifying key questions, and image generation. Our human editors guided topic selection, defined the angle, structured the content, ensured factual accuracy and relevance, refined the tone, and conducted thorough editing to deliver helpful, high-quality information.See our About page for more information.

This article is based on research published under:

DOI-LINK: 10.1590/s1679-45082011ao2097, Alternate LINK

Title: Measurement Of The Palpebral Fissure And The Vermilion Border Of The Upper Lip In Newborns With Gestational Ages Of 25 To 43 Weeks

Subject: General Medicine

Journal: Einstein (São Paulo)

Publisher: FapUNIFESP (SciELO)

Authors: Maria Dos Anjos Mesquita, Conceição Aparecida De Mattos Segre

Published: 2011-09-01

Everything You Need To Know

What specific facial measurements are crucial for assessing newborn health?

The critical facial measurements for newborn health assessment, as highlighted by researchers like Maria dos Anjos Mesquita and Conceição Aparecida de Mattos Segre, are the length of the palpebral fissure (the eye opening) and the width of the vermilion border of the upper lip (the red part). These measurements are essential in identifying potential dysmorphic characteristics, which can be indicative of underlying health issues or developmental conditions. They provide valuable data points for healthcare professionals to evaluate a newborn's overall well-being.

How is the palpebral fissure measured, and what does it signify in newborns?

The palpebral fissure is measured from the inner corner (endocanthion) to the outer corner (exocanthion) of the eye. This measurement, along with the vermilion border width, is used to assess if a newborn's facial features are within the typical range. The significance lies in its potential to reveal facial dysmorphism, which could be linked to certain syndromes or developmental issues. Measurements outside the established percentile curves might prompt further evaluation to ensure the baby receives appropriate care and support if needed.

What are the typical measurement ranges for the palpebral fissure and vermilion border in newborns, according to the study?

The study by Mesquita and Segre established typical ranges for facial measurements in newborns. For the palpebral fissure, the average measurement was 1.98 cm, with a range of 0.80 to 3.00 cm. The vermilion border's average width was 0.51 cm, ranging from 0.20 to 0.90 cm. These values were obtained from a large sample of 1,964 newborns and used to create percentile curves for reference.

Why is early detection of facial dysmorphism important, and how do measurements help with this?

Early detection of facial dysmorphism is crucial because it enables timely intervention and support for newborns who may have underlying health conditions. The measurements of the palpebral fissure and vermilion border assist in this by providing quantifiable data points that can be compared against established percentile curves. If a newborn's measurements fall outside the typical ranges, it may indicate dysmorphic features that warrant further investigation. This early identification allows healthcare professionals to diagnose conditions promptly and initiate appropriate treatment, improving outcomes for the child.

How do researchers like Mesquita and Segre use measurements to assess newborn health, and what is the role of percentile curves?

Researchers like Maria dos Anjos Mesquita and Conceição Aparecida de Mattos Segre measured the palpebral fissure and vermilion border in a large cohort of newborns to create standard measurement curves. These curves, which illustrate the distribution of measurements across different gestational ages, serve as a reference for healthcare providers. By comparing a newborn's specific facial measurements to these percentile curves, clinicians can determine if they fall within the expected range, aiding in identifying potential dysmorphic features. This process helps detect newborns who may need further evaluation and potentially early intervention for underlying health conditions.