From trying to conceive through the third trimester, the number of dates and measurements to track keeps growing: menstrual cycles, fertile windows, last menstrual period, gestational age, due date, fetal biparietal diameter, abdominal circumference, femur length, estimated weight, and more.
This information is often scattered across calendars, ultrasound reports, and reference charts, making it easy to confuse units, pregnancy dating methods, or examination dates when searching on the fly. Here are 12 fertility and pregnancy tools organized in the order you are most likely to use them, helping you keep everyday records and understand essential measurements.
Before you begin, remember that online calculations are intended only to organize information and support understanding. They cannot replace a diagnosis from an obstetrician. Gestational age adjustments, fetal growth assessments, and abnormal results should always be reviewed through professional prenatal care and with your doctor.
1. Trying to Conceive: Understand Your Cycle and Ovulation
1. Ovulation Calculator
The Ovulation Calculator uses the date of your last menstrual period and average cycle length to estimate your ovulation date, fertile window, and next period. It can help people with relatively regular cycles plan a fertility calendar, but sleep patterns, stress, and overall health can affect ovulation, so predicted dates are not medical confirmation.
2. Follicle Diameter Calculator
The Follicle Diameter Calculator helps you record follicle measurements from different monitoring dates and track how quickly they change. It is best used as a log for ultrasound monitoring. Confirming ovulation still requires a clinician’s interpretation alongside hormone tests and serial ultrasound results.
3. Progesterone Reference Tool
The Progesterone Reference Tool provides common reference information by reproductive or pregnancy stage, helping you understand the units and ranges shown on laboratory reports. Reference ranges may vary by laboratory, testing method, and gestational age, so always use the range printed on your own report first.
2. After a Positive Pregnancy Test: Calculate Gestational Age and Due Date
4. Gestational Age Calculator
The Gestational Age Calculator typically counts from the first day of your last menstrual period to determine how many weeks and days pregnant you are. It also provides an approximate conception date. A common mistake is using the date of intercourse or a positive pregnancy test as the starting point.
5. Pregnancy Due Date Calculator
The Pregnancy Due Date Calculator estimates your due date from your last menstrual period or another relevant date, helping you plan prenatal appointments, parental leave, and birth preparations. A due date is only an estimate—it does not mean your baby will arrive on that exact day. If your periods are irregular, your clinician may adjust the pregnancy dating based on an early ultrasound.
6. Pregnancy Week-by-Week Reference
The Pregnancy Week-by-Week Reference shows the first, second, and third trimesters in one chart. It offers a clearer answer to questions such as “How many months is 24 weeks pregnant?” and “How long until full term?” while reducing confusion between pregnancy weeks and calendar months.
3. Understanding Ultrasound and Prenatal Records: Focus on Trends
7. Fetal Growth Chart
The Fetal Growth Chart organizes common fetal measurements by gestational age and explains reference information for abbreviations such as biparietal diameter, head circumference, abdominal circumference, and femur length. When assessing growth, trends across multiple prenatal visits matter more than comparing a single result with an online chart.
8. Estimated Fetal Weight Calculator
The Estimated Fetal Weight Calculator uses ultrasound measurements such as BPD, HC, AC, and FL to estimate fetal weight. A reasonable margin of error is expected, and even close to delivery, the estimated weight in grams should not be treated as the baby’s actual birth weight.
9. Fetal Cerebroplacental Ratio Calculator
The Fetal Cerebroplacental Ratio Calculator calculates specialized measurements such as the fetal cerebroplacental ratio and helps organize data from Doppler ultrasound reports. An obstetrician or ultrasound specialist must interpret these results alongside gestational age, blood-flow measurements, and other findings. Do not draw conclusions from a single ratio on your own.
4. Essential Pregnancy Tracking: Weight, Body Surface Area, and Blood Pressure
10. BMI Calculator
The BMI Calculator calculates body mass index from height and weight, making it useful for recording your baseline health before pregnancy or at your first prenatal visit. Weight changes follow different patterns during pregnancy, so a standard adult BMI alone cannot determine whether pregnancy weight gain is appropriate.
11. Body Surface Area Calculator
The Body Surface Area Calculator estimates BSA from height and weight. BSA is used in certain medical tests, medication calculations, and clinical references, but it is not an everyday measure of fetal development. You can use the tool to understand how BSA on a report was calculated, but never adjust medication without medical guidance.
12. Blood Pressure Calculator
The Blood Pressure Calculator helps you organize systolic pressure, diastolic pressure, and mean arterial pressure readings. Blood pressure should be measured correctly and tracked throughout pregnancy. Seek prompt medical care if abnormal readings recur or are accompanied by symptoms such as headache, vision changes, or swelling.
How to Organize Your Pregnancy Records
Consider using these tools in three groups: the ovulation, gestational age, and due date calculators for tracking important dates; the fetal growth, estimated weight, and cerebroplacental ratio tools for understanding prenatal reports; and the BMI, body surface area, and blood pressure calculators for monitoring maternal health.
The National Standards for Maternal Healthcare issued by China’s National Health Commission emphasize maintaining maternity health records, attending regular prenatal checkups, and screening for risk factors. These tools are most useful for organizing dates and measurements; qualified healthcare professionals should make all clinical risk assessments.
Bookmark this collection for quick access whenever you need to check your gestational age, estimate your due date, or understand an ultrasound measurement.