During pregnancy, measuring fetal growth and development is essential to ensure a healthy delivery and baby. One important measurement taken during ultrasound scans is the occipito-frontal diameter (OFD). In this blog post, we’ll explore what the occipito-frontal diameter is, why it’s important, and how it’s used in prenatal diagnosis and neonatal care.
What is the Occipito-Frontal Diameter (OFD)?
The occipito-frontal diameter is the distance between the occipital bone (back of the head) and the forehead. It is measured during an ultrasound scan using a special caliper tool that is placed on the fetal head. The measurement is taken in a plane that is perpendicular to the long axis of the fetus.
Occipitofrontal Diameter (mm)
| Gestational age (exact weeks) |
3rd | 5th | 10th | 50th | 90th | 95th | 97th |
| 14 | 30.12 | 30.58 | 31.28 | 33.76 | 36.24 | 36.94 | 37.40 |
| 15 | 34.37 | 34.86 | 35.62 | 38.29 | 40.96 | 41.72 | 42.21 |
| 16 | 38.64 | 39.16 | 39.98 | 42.83 | 45.69 | 46.51 | 47.03 |
| 17 | 42.89 | 43.45 | 44.32 | 47.36 | 50.40 | 51.27 | 51.83 |
| 18 | 47.13 | 47.72 | 48.64 | 51.86 | 55.08 | 55.99 | 56.58 |
| 19 | 51.32 | 51.95 | 52.91 | 56.30 | 59.70 | 60.66 | 61.28 |
| 20 | 55.47 | 56.12 | 57.14 | 60.69 | 64.24 | 65.26 | 65.91 |
| 21 | 59.55 | 60.23 | 61.28 | 65.00 | 68.71 | 69.77 | 70.45 |
| 22 | 63.54 | 64.25 | 65.35 | 69.21 | 73.07 | 74.17 | 74.88 |
| 23 | 67.43 | 68.17 | 69.31 | 73.32 | 77.32 | 78.46 | 79.20 |
| 24 | 71.22 | 71.98 | 73.16 | 77.30 | 81.45 | 82.63 | 83.39 |
| 25 | 74.87 | 75.66 | 76.88 | 81.16 | 85.44 | 86.66 | 87.44 |
| 26 | 78.39 | 79.20 | 80.45 | 84.87 | 89.28 | 90.54 | 91.35 |
| 27 | 81.74 | 82.58 | 83.87 | 88.42 | 92.96 | 94.26 | 95.10 |
| 28 | 84.93 | 85.79 | 87.12 | 91.80 | 96.49 | 97.82 | 98.68 |
| 29 | 87.93 | 88.81 | 90.19 | 95.01 | 99.83 | 101.21 | 102.09 |
| 30 | 90.73 | 91.64 | 93.06 | 98.03 | 103.00 | 104.42 | 105.33 |
| 31 | 93.31 | 94.26 | 95.72 | 100.85 | 105.98 | 107.44 | 108.38 |
| 32 | 95.67 | 96.64 | 98.15 | 103.46 | 108.77 | 110.28 | 111.25 |
| 33 | 97.77 | 98.78 | 100.35 | 105.85 | 111.35 | 112.92 | 113.93 |
| 34 | 99.62 | 100.67 | 102.30 | 108.02 | 113.74 | 115.37 | 116.42 |
| 35 | 101.19 | 102.28 | 103.98 | 109.95 | 115.92 | 117.62 | 118.71 |
| 36 | 102.45 | 103.60 | 105.38 | 111.63 | 117.89 | 119.67 | 120.82 |
| 37 | 103.40 | 104.61 | 106.49 | 113.07 | 119.65 | 121.52 | 122.73 |
| 38 | 104.02 | 105.29 | 107.28 | 114.24 | 121.20 | 123.18 | 124.46 |
| 39 | 104.26 | 105.62 | 107.74 | 115.14 | 122.55 | 124.66 | 126.02 |
| 40 | 104.12 | 105.58 | 107.84 | 115.77 | 123.70 | 125.96 | 127.42 |
Why is the Occipito-Frontal Diameter Important?
The occipito-frontal diameter is an important measurement because it provides information about the fetal head size and growth. Abnormalities in the OFD can indicate potential issues such as microcephaly (small head size) or macrocephaly (large head size). These abnormalities can be caused by genetic disorders, infections, or other conditions that can affect fetal development.
The OFD is also used to monitor fetal growth and estimate fetal weight. This information is important for determining if the baby is growing properly and if there are any concerns about the baby’s size or health. It can also help doctors and midwives plan for a safe delivery and determine if there are any risks that may require special care during or after delivery.
How is the Occipito-Frontal Diameter Used in Prenatal Diagnosis and Neonatal Care?
The occipito-frontal diameter is a key measurement in prenatal diagnosis and neonatal care. During pregnancy, the OFD is measured during routine ultrasound scans to monitor fetal growth and development. If there are any concerns about the OFD measurement, further testing may be recommended, such as amniocentesis or genetic testing.
In neonatal care, the OFD is used to assess the newborn’s head size and growth. This can help doctors and nurses determine if there are any concerns about the baby’s health or if special care is needed. For example, if a newborn has a small head size (microcephaly), this may indicate a potential neurological issue that requires further evaluation and treatment.
In conclusion, the occipito-frontal diameter is an important measurement in prenatal diagnosis and neonatal care. It provides information about fetal growth and can help identify potential issues that require further evaluation and treatment. If you have any concerns about your pregnancy or your baby’s health, talk to your healthcare provider. Regular prenatal care and monitoring can help ensure a healthy pregnancy and delivery.