Tracking a pregnancy means knowing where you are in the timeline, monitoring your body’s changes, and staying on top of the checkups that matter at each stage. The full journey spans about 40 weeks from the first day of your last menstrual period, divided into three trimesters with distinct milestones. Here’s how to follow along from the earliest positive test through delivery.
Calculating Your Due Date
Your due date is the anchor for everything else. The standard method, called Naegele’s Rule, works in three steps: take the first day of your last menstrual period, count back three calendar months, then add one year and seven days. If your last period started June 10, you’d count back to March 10, then add a year and seven days to land on March 17 of the following year.
This formula assumes a 28-day menstrual cycle. If your cycles run longer or shorter, the estimate shifts. Someone with a 35-day cycle, for instance, ovulates about a week later than someone with a 28-day cycle, so the due date would move forward by roughly a week. An early ultrasound, typically done between 8 and 12 weeks, can refine the estimate by measuring the embryo directly. Most providers consider the ultrasound date more reliable than the calendar method if the two differ by more than a week.
Understanding the Three Trimesters
The first trimester runs from the first day of your last period through 13 weeks and 6 days. This is when fertilization happens, and all major organs begin forming. It’s also the window where symptoms tend to hit hardest: extreme tiredness, nausea (with or without vomiting), tender and swollen breasts, food cravings or aversions, mood swings, constipation, frequent urination, headaches, and heartburn. Not everyone gets all of these, and their intensity varies widely. Most of these symptoms ease by the end of the first trimester as hormone levels stabilize.
The second trimester covers weeks 14 through 27. This is a period of rapid growth and development for the baby, and many people feel their best during these weeks. You’ll likely start showing, and somewhere between weeks 18 and 22, you may feel the first flutters of movement. The detailed anatomy scan ultrasound usually falls around week 20, giving a thorough look at the baby’s organs, limbs, and growth.
The third trimester spans weeks 28 through 40. The baby is gaining weight and organs are maturing in preparation for life outside the womb. You’ll feel more movement (and more pressure on your bladder, ribs, and back). This is also the stage where tracking fetal movement becomes important, which we’ll cover below.
Keeping Up With Prenatal Visits
Starting prenatal care before 10 weeks is ideal. Early visits establish baseline measurements like your blood pressure, weight, and blood type, and they screen for conditions that could affect the pregnancy. The traditional schedule calls for monthly visits through the seventh month, then more frequent appointments from the eighth month until delivery. For pregnancies without complications, some of these check-ins may happen via telehealth for general counseling, with in-person visits reserved for physical exams and specific tests.
Key screenings fall at predictable points. In the first trimester, blood tests and sometimes an early ultrasound confirm gestational age and screen for chromosomal conditions. Between weeks 24 and 28, a glucose screening checks for gestational diabetes. In the third trimester, a test for Group B strep typically happens around weeks 35 to 37. Keeping a simple calendar or checklist of these appointments helps you stay ahead of scheduling, especially since popular clinics can book up weeks in advance.
Tracking Weight Gain
How much weight you should expect to gain depends on your pre-pregnancy BMI. The current guidelines from the CDC, based on Institute of Medicine recommendations, break down as follows for a single baby:
- Underweight (BMI under 18.5): 28 to 40 pounds
- Normal weight (BMI 18.5 to 24.9): 25 to 35 pounds
- Overweight (BMI 25.0 to 29.9): 15 to 25 pounds
- Obese (BMI 30.0 to 39.9): 11 to 20 pounds
For twins, the ranges are significantly higher. A person with a normal pre-pregnancy BMI carrying twins would aim for 37 to 54 pounds. Weight gain isn’t linear. Many people gain very little (or even lose weight) in the first trimester due to nausea, then add about a pound per week in the second and third trimesters. Tracking your weight weekly or biweekly at home, ideally at the same time of day, helps you spot trends without fixating on daily fluctuations.
Monitoring Blood Pressure
Blood pressure is one of the most important numbers to watch throughout pregnancy because changes can signal preeclampsia, a serious condition that develops after 20 weeks. Normal blood pressure is below 120/80 mm Hg. Readings between 120-129 systolic (the top number) with a diastolic (bottom number) under 80 are considered elevated. Once the top number hits 130 or the bottom number reaches 80, that’s stage 1 hypertension. At 140/90 or above, it’s stage 2.
Your provider will check your blood pressure at every prenatal visit. If you have risk factors for preeclampsia (such as a history of high blood pressure, carrying multiples, or a first pregnancy), a home blood pressure cuff lets you track readings between visits. Write down the numbers along with the date and time so you have a log to share at appointments. A sudden spike, especially paired with symptoms like severe headache, vision changes, or swelling in the face or hands, warrants immediate contact with your provider.
Counting Kicks in the Third Trimester
Starting around week 28, tracking your baby’s movements gives you a daily snapshot of their well-being. There are two common methods: count how many movements you feel in one hour, or time how long it takes to reach 10 movements. Ten kicks, flutters, or rolls in one hour is considered typical.
Pick a time when the baby is usually active (many people notice more movement after eating or in the evening). Sit or lie down in a comfortable position, start a timer, and make a mark on paper or in an app each time you feel movement. Once you hit 10, note how many minutes it took. Over a few days, you’ll start to recognize your baby’s pattern. A consistent pattern matters more than hitting exactly 10 in exactly one hour. What you’re looking for is a noticeable change from that pattern, like a day where the baby is significantly less active than usual.
What to Log Daily
Whether you use a paper journal, a spreadsheet, or a pregnancy app, the most useful daily data points are your symptoms, weight (weekly is enough), blood pressure (if you’re monitoring at home), fetal movement counts once you’re in the third trimester, and notes on nutrition, hydration, and sleep quality. Pregnancy apps can send reminders, store photos, and provide personalized tools to assess nutrition, fitness, and weight, which makes them convenient for daily logging.
The real value of tracking isn’t the data itself. It’s the patterns. A journal entry that says “nausea worse this week, only sleeping five hours” might not mean much alone, but over several weeks it can reveal triggers or trends worth mentioning to your provider. Bringing a concise log to prenatal visits also makes those appointments more productive. Instead of trying to remember how you felt three weeks ago, you have a record.
Early Pregnancy: What Blood Tests Reveal
In the very early weeks, before ultrasounds can show much, blood tests measuring hCG (the hormone your body produces after implantation) are the main way to confirm a pregnancy is progressing. The levels change dramatically week to week. At four weeks, hCG typically ranges from 0 to 750 µ/L. By five weeks, it rises to 200 to 7,000 µ/L. At six weeks, the range is 200 to 32,000 µ/L, and by seven weeks it can reach 3,000 to 160,000 µ/L. Between weeks 8 and 12, levels plateau between roughly 32,000 and 210,000 µ/L.
These ranges are extremely wide, which is normal. What matters more than any single number is whether the level is rising appropriately. In a healthy early pregnancy, hCG roughly doubles every 48 to 72 hours. Providers sometimes order two blood draws a couple of days apart to confirm this trend. After the first trimester, hCG tracking becomes less relevant because ultrasounds take over as the primary way to monitor development.