How to use the Pregnancy Due Date Calculator
- Select the date of the first day of your last menstrual period in the space provided.
- Select your average menstrual cycle length from the dropdown menu.
- Your due date, the gestational age (age from conception to birth) of your baby, and a trimester timeline will appear in the window next to the calculator.
- Click reset to start over.
A typical pregnancy (gestation) lasts 40 weeks from the first day of your last menstrual period to the birth of your baby. Pregnancy is divided into three stages, called trimesters: first trimester, second trimester, and third trimester. You and your baby will experience changes throughout the three trimesters.
First Trimester: Week 1 (conception) – Week 12
- Extreme fatigue
- Tender, swollen breasts
- Nausea with or without vomiting
- Cravings or aversion to certain foods
- Mood swings
- Frequent urination
- Weight gain or loss
Some of the changes you experience in your first trimester may cause you to revise your daily routine. You may need to go to bed earlier or eat more frequent or smaller meals. Some women experience a lot of discomforts, while others feel no discomfort at all. Pregnant women experience pregnancy differently even if they have been pregnant before. Pregnant women may feel completely different with each subsequent pregnancy.
Your baby is now an embryo at 1/25 of an inch long and begins to develop:
- The nervous system (brain and spinal cord)
- The heart
- Arm and leg buds
The embryo begins to develop into a fetus. Fetal development entails:
- All major organs have begun to form.
- The baby's heart begins to beat.
- The arms and legs grow longer.
- Fingers and toes have begun to form.
- Sex organs begin to form.
- The face begins to develop features.
- The umbilical cord is clearly visible.
By the end of Week 8, the baby is a fetus, is nearly 1 inch long, and weighs less than an ounce.
Your baby is now about 3 inches long and weighs almost 1 ounce. By week 12:
- The nerves and muscles begin to work together. Your baby can make a fist.
- The external sex organs show if your baby is a boy or girl.
- Eyelids close to protect the developing eyes. They will not open again until week 28.
- Head growth has slowed.
Second trimester: Week 13 – Week 28
Your nausea (morning sickness) and fatigue may lessen or go away completely, and you may notice more changes to your body. Your "baby bump" will start to show as your abdomen expands with the growing baby. By the end of the second trimester, you may feel your baby move.
Some changes you may notice in your body in the second trimester include:
- Back, abdomen, groin, or thigh aches and pains
- Stretch marks on your abdomen, breasts, thighs, or buttocks
- Darkening of the skin around your nipples
- A line on the skin running from belly button to pubic hairline
- Patches of darker skin, usually over the cheeks, forehead, nose, or upper lip
- Numb or tingling hands
- Itching on the abdomen, palms, and soles of the feet
- Swelling of the ankles, fingers, and face
If you notice any sudden or extreme swelling or if you gain a lot of weight quickly, call your doctor immediately. This could be a sign of a serious condition called preeclampsia.
Your baby is now about 4 to 5 inches long and weighs almost 3 ounces. Further developments include:
- The musculoskeletal system continues to form.
- Skin begins to form and is nearly translucent.
- Meconium develops in your baby's intestinal tract. This will be your baby's first bowel movement.
- Your baby begins sucking motions with the mouth (the sucking reflex).
Now halfway through your pregnancy, your baby is about 6 inches long and weighs about 9 ounces. This means:
- Your baby is more active. You might feel movement or kicking.
- Your baby is covered by fine, feathery hair called lanugo and a waxy protective coating called vernix.
- Eyebrows, eyelashes, fingernails, and toenails have formed. Your baby can even scratch himself/herself.
- Your baby can hear and swallow.
Your baby now stores fat, weighs about 1½ pounds and is 12 inches long. Developments include:
- The baby's bone marrow begins to make blood cells.
- Taste buds form on your baby's tongue.
- Footprints and fingerprints have formed.
- Hair begins to grow on your baby's head.
- Although the lungs have begun to form, they do not yet work.
- Your baby has a regular sleep cycle.
- If your baby is a boy, his testicles begin to descend into the scrotum.
- If your baby is a girl, her uterus and ovaries are in place, and a lifetime supply of eggs has formed in the ovaries.
Third Trimester: Week 29 – Week 40 (birth)
The third trimester is the final stage of pregnancy. Discomforts that started in the second trimester will likely continue, along with some new ones. As the baby grows and puts more pressure on your internal organs, you may find you have difficulty breathing and have to urinate more frequently. These problems are normal and should go away once you give birth. You may notice other physical changes, including:
- Swelling of the ankles, fingers, and face
- Tender breasts, which may leak a watery pre-milk called colostrum
- A protruding belly button
- The baby "dropping," or moving lower in your abdomen
- Contractions, which can be a sign of real or false labor
- Shortness of breath, heartburn, and difficulty sleeping
Other changes are happening in your body during the third trimester that you can't see. As your due date approaches, your cervix becomes thinner and softer in a process called effacement that helps the cervix open during childbirth. Your doctor will monitor the progress of your pregnancy with regular exams, especially as you near your due date.
If you notice any sudden or extreme swelling or if you gain a lot of weight really quickly, call your doctor right away. This could be a sign of a serious condition called preeclampsia.
Your baby now gains about ½ pounds a week, weighs about 4 to 4½ pounds, and is about 15 to 17 inches long.
- Your baby's bones are soft but fully formed.
- Movements and kicking increase.
- Your baby's eyes can open and close.
- Although the lungs have not fully formed, practice "breathing" movements occur.
- Your baby's body begins to store vital minerals, such as iron and calcium.
- Lanugo (fine hair) begins to fall off.
Your baby is now about 16 to 19 inches long and weighs about 6 to 6½ pounds.
- The protective waxy coating (vernix) thickens.
- Body fat increases.
- Because your baby is getting bigger and has less space to move, movements are less forceful, but you will still feel them.
By the end of 37 weeks, your baby is considered full term. This means:
- Your baby's organs are capable of functioning on their own.
As you near your due date, your baby may turn into a head-down position for birth.
The average birth weight is between 6 pounds 2 ounces to 9 pounds 2 ounces and the average length is 19 to 21 inches long. Most full-term babies fall within these ranges, but healthy babies come in many different weights and sizes.
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Womenshealth.gov: Centers for Disease Control and Prevention (CDC): "Stages of Pregnancy."
National Institutes of Health