UNDERSTANDING DUE DATES AND TRIMESTERS
After announcing your pregnancy, the first question often is, "When is your due date?" Your healthcare provider will calculate your estimated delivery date (EDD) during your first prenatal visit, typically set at 40 weeks from the first day of your last menstrual period (LMP).
Keep in mind that your due date is an estimate; most babies are born between 38 and 42 weeks after the LMP, with only a small percentage arriving on their exact due date.
Pregnancy is divided into three trimesters:
PREGNANCY CALENDAR: A week-by-week guide
1Week 1: Preparing for Conception
The first week of pregnancy aligns with your menstrual period. Although conception hasn't occurred yet, this week is included in the 40-week pregnancy count, as the estimated due date (EDD) is calculated from the first day of your last menstrual period (LMP). Knowing your LMP helps determine your due date using a gestational calculator.
The first week of pregnancy aligns with your menstrual period. Although conception hasn't occurred yet, this week is included in the 40-week pregnancy count, as the estimated due date (EDD) is calculated from the first day of your last menstrual period (LMP). Knowing your LMP helps determine your due date using a gestational calculator.
2Week 2: Conception
Fertilization occurs near the end of this week as the sperm meets the egg, marking the beginning of conception.
Fertilization occurs near the end of this week as the sperm meets the egg, marking the beginning of conception.
3Week 3: Early Development
Thirty hours after fertilization, the zygote (fertilized egg) divides into two cells. By day three, it forms 16 cells and migrates from the fallopian tube to the uterus. On day seven, it implants into the uterine lining, becoming a blastocyst.
Thirty hours after fertilization, the zygote (fertilized egg) divides into two cells. By day three, it forms 16 cells and migrates from the fallopian tube to the uterus. On day seven, it implants into the uterine lining, becoming a blastocyst.
4Week 4: Rapid Cell Growth
The developing baby is smaller than a grain of rice. Cells are dividing rapidly and beginning to form major body systems, including the digestive system.
The developing baby is smaller than a grain of rice. Cells are dividing rapidly and beginning to form major body systems, including the digestive system.
5Week 5: Neural Development
The neural tube, which will form the brain and spinal cord, begins to develop.
The neural tube, which will form the brain and spinal cord, begins to develop.
6Week 6: Embryo Stage
The baby is now classified as an embryo and measures approximately 3 mm in length. It produces hormones that stop the menstrual cycle.
The baby is now classified as an embryo and measures approximately 3 mm in length. It produces hormones that stop the menstrual cycle.
7Week 7: Heartbeat and Placenta
The embryo's heart begins to beat. The placenta and amniotic sac are now fully developed, with the placenta drawing oxygen and nutrients from the mother's bloodstream.
The embryo's heart begins to beat. The placenta and amniotic sac are now fully developed, with the placenta drawing oxygen and nutrients from the mother's bloodstream.
8Week 8: Growth and Proportions
The embryo grows to about 1.3 cm in length. The spinal cord develops rapidly, and the head appears disproportionately large.
The embryo grows to about 1.3 cm in length. The spinal cord develops rapidly, and the head appears disproportionately large.
9Week 9: Early Features
The eyes, mouth, and tongue begin forming. Muscles develop, enabling small movements. Blood cells are produced in the liver.
The eyes, mouth, and tongue begin forming. Muscles develop, enabling small movements. Blood cells are produced in the liver.
10Week 10: Fetal Stage Begins
The embryo is now called a fetus and measures about 2.5 cm in length. All organs are formed, fingers and toes develop from paddle-like structures, and brain activity is detectable.
The embryo is now called a fetus and measures about 2.5 cm in length. All organs are formed, fingers and toes develop from paddle-like structures, and brain activity is detectable.
11Week 11: Teeth and Heart Development
Teeth start forming under the gums, and the heart becomes more intricate.
Teeth start forming under the gums, and the heart becomes more intricate.
12Week 12: First Trimester Screening
Fingers and toes are distinct but may still have slight webbing. The first trimester screening for chromosomal abnormalities, including trisomy 18 and trisomy 21, can be performed.
Fingers and toes are distinct but may still have slight webbing. The first trimester screening for chromosomal abnormalities, including trisomy 18 and trisomy 21, can be performed.
13Week 13: Active Movements
The fetus measures over 7 cm and can move vigorously.
The fetus measures over 7 cm and can move vigorously.
14Week 14: Vocal Cords and Nails
The baby has vocal cords and may begin to suck its thumb. Eyelids remain fused, and nails form on the fingers and toes.
The baby has vocal cords and may begin to suck its thumb. Eyelids remain fused, and nails form on the fingers and toes.
15Week 15: Delicate Skin & Growing Strength
Your baby's skin is soft, thin, and translucent, with visible blood vessels. Hair continues to grow on the head and eyebrows, and ears are nearly in place. The skeletal system strengthens, and muscle development allows for active movements of the head, mouth, arms, and legs.
Your baby's skin is soft, thin, and translucent, with visible blood vessels. Hair continues to grow on the head and eyebrows, and ears are nearly in place. The skeletal system strengthens, and muscle development allows for active movements of the head, mouth, arms, and legs.
16Week 16: Facial Features and Screening
The fetus is around 14 cm long, with eyelashes, eyebrows, and taste buds. If not done earlier, maternal serum screening may be performed at this stage.
The fetus is around 14 cm long, with eyelashes, eyebrows, and taste buds. If not done earlier, maternal serum screening may be performed at this stage.
17Week 17: Placenta Growth & Baby's Development
At about 5.1 inches (13 cm) long and weighing 4.9 ounces (140 grams), your baby is still small. The placenta continues to grow, filled with thousands of blood vessels that deliver essential nutrients and oxygen while removing waste.
At about 5.1 inches (13 cm) long and weighing 4.9 ounces (140 grams), your baby is still small. The placenta continues to grow, filled with thousands of blood vessels that deliver essential nutrients and oxygen while removing waste.
18Week 18: Anatomy Scan
An ultrasound is conducted to examine the baby’s structure, detect abnormalities, and determine the placenta’s position. Hiccups may be visible during this scan.
An ultrasound is conducted to examine the baby’s structure, detect abnormalities, and determine the placenta’s position. Hiccups may be visible during this scan.
19Week 19: Feeling Baby's First Movements
Between weeks 18 and 20, you may feel your baby's first movements, known as quickening. These gentle flutters may feel like butterflies or a growling stomach. As pregnancy progresses, you'll notice stronger kicks, punches, and even hiccups!
Between weeks 18 and 20, you may feel your baby's first movements, known as quickening. These gentle flutters may feel like butterflies or a growling stomach. As pregnancy progresses, you'll notice stronger kicks, punches, and even hiccups!
20Week 20: Hearing Develops
The fetus measures 21 cm. Its ears are fully functional, and unique fingerprints form. Genital development can be observed via ultrasound.
The fetus measures 21 cm. Its ears are fully functional, and unique fingerprints form. Genital development can be observed via ultrasound.
21Week 21: Amniotic Fluid and Baby's Digestion
Amniotic fluid now aids digestion as your baby swallows it. Sugars are absorbed through the intestines and passed to the large bowel, signaling digestive development.
Amniotic fluid now aids digestion as your baby swallows it. Sugars are absorbed through the intestines and passed to the large bowel, signaling digestive development.
22Week 22: Developing Senses and Reproductive System
Your baby’s senses are growing rapidly, with taste buds forming and the ability to feel touch. They may explore by sucking a thumb or stroking their face. Meanwhile, the reproductive system advances—testes descend in boys, and the uterus, ovaries, and vagina are developed in girls.
Your baby’s senses are growing rapidly, with taste buds forming and the ability to feel touch. They may explore by sucking a thumb or stroking their face. Meanwhile, the reproductive system advances—testes descend in boys, and the uterus, ovaries, and vagina are developed in girls.
23Week 23: Growth, Movement, and Premature Survival
Your baby, now over 1 pound, develops fat but retains wrinkled skin. Muscle movements become stronger, and you may feel more forceful kicks. If born this week, survival is possible with medical care, though challenges may vary. Advances in fetal medicine continue to improve outcomes for preemies.
Your baby, now over 1 pound, develops fat but retains wrinkled skin. Muscle movements become stronger, and you may feel more forceful kicks. If born this week, survival is possible with medical care, though challenges may vary. Advances in fetal medicine continue to improve outcomes for preemies.
24Week 24: Eyelids and Skin Changes
The fetus, now around 33 cm, begins opening and closing its eyes. Fine hair (lanugo) and a protective waxy coating (vernix) cover its skin. Breathing movements are visible.
The fetus, now around 33 cm, begins opening and closing its eyes. Fine hair (lanugo) and a protective waxy coating (vernix) cover its skin. Breathing movements are visible.
25Week 25: Baby's Activity and Hearing
Your baby now has rest and alert periods, with movements more noticeable when you’re still. Their hearing has developed enough to recognize your voice!
Your baby now has rest and alert periods, with movements more noticeable when you’re still. Their hearing has developed enough to recognize your voice!
26Week 26: Eyes Opening and Weight Gain
Your baby’s eyes will soon open, with lashes and hair growing. Eye color at birth may change in the first year. Now weighing nearly 2 pounds, your baby will steadily gain weight until birth.
Your baby’s eyes will soon open, with lashes and hair growing. Eye color at birth may change in the first year. Now weighing nearly 2 pounds, your baby will steadily gain weight until birth.
27Week 27: Third Trimester Milestones
By now, your baby resembles their birth appearance but is thinner and smaller. While the lungs, liver, and immune system are still maturing, survival chances are strong if born now. Hearing develops further, with sounds muffled by the protective vernix coating.
By now, your baby resembles their birth appearance but is thinner and smaller. While the lungs, liver, and immune system are still maturing, survival chances are strong if born now. Hearing develops further, with sounds muffled by the protective vernix coating.
28Week 28: Significant Growth
The baby weighs about 1 kg and measures 25 cm from crown to rump, or 37 cm from head to toe. Its body is now proportionate.
The baby weighs about 1 kg and measures 25 cm from crown to rump, or 37 cm from head to toe. Its body is now proportionate.
29Week 29: Monitoring Baby's Movements
Your baby’s movements are now stronger, with jabs and punches. If movement decreases, do a kick count—at least 10 movements in 2 hours. Contact your healthcare provider if there’s less activity.
Your baby’s movements are now stronger, with jabs and punches. If movement decreases, do a kick count—at least 10 movements in 2 hours. Contact your healthcare provider if there’s less activity.
30Week 30: Weight Gain and Breathing Preparation
Now weighing about 3 pounds and measuring 10.8 inches, your baby continues to gain weight and develop fat layers, reducing wrinkling and providing warmth after birth. They practice breathing by moving the diaphragm and may experience hiccups, felt as rhythmic twitches in your uterus.
Now weighing about 3 pounds and measuring 10.8 inches, your baby continues to gain weight and develop fat layers, reducing wrinkling and providing warmth after birth. They practice breathing by moving the diaphragm and may experience hiccups, felt as rhythmic twitches in your uterus.
31Week 31: Amniotic Fluid Dynamics
Your baby is producing several cups of urine daily, which mixes with the amniotic fluid they swallow, replenished multiple times a day. Abnormal fluid levels—too much (polyhydramnios) or too little (oligohydramnios)—could indicate potential issues. Your healthcare provider will monitor amniotic fluid levels during routine ultrasounds.
Your baby is producing several cups of urine daily, which mixes with the amniotic fluid they swallow, replenished multiple times a day. Abnormal fluid levels—too much (polyhydramnios) or too little (oligohydramnios)—could indicate potential issues. Your healthcare provider will monitor amniotic fluid levels during routine ultrasounds.
32Week 32: Sleep and Movement
The baby spends most of its time sleeping but demonstrates strong and coordinated movements.
The baby spends most of its time sleeping but demonstrates strong and coordinated movements.
33Week 33: Brain Development and Final Preparations
In the weeks leading up to delivery, your baby's brain develops billions of neurons, enabling them to listen, feel, and perceive light. They experience REM sleep, similar to newborns, and their lungs are nearly fully matured. Fat accumulation continues, providing protection and warmth as significant weight gain occurs before birth.
In the weeks leading up to delivery, your baby's brain develops billions of neurons, enabling them to listen, feel, and perceive light. They experience REM sleep, similar to newborns, and their lungs are nearly fully matured. Fat accumulation continues, providing protection and warmth as significant weight gain occurs before birth.
34Week 34: Importance of Calcium and Baby's Position
Maternal calcium intake is crucial during pregnancy, as your baby needs it to develop strong bones. Ensure you consume calcium-rich foods like dairy, tofu, and fortified juices alongside your prenatal vitamins. Most babies are now positioned for delivery, with 34-week-olds typically having developed lungs and averaging 5 pounds, allowing for survival outside the womb with minimal medical support.
Maternal calcium intake is crucial during pregnancy, as your baby needs it to develop strong bones. Ensure you consume calcium-rich foods like dairy, tofu, and fortified juices alongside your prenatal vitamins. Most babies are now positioned for delivery, with 34-week-olds typically having developed lungs and averaging 5 pounds, allowing for survival outside the womb with minimal medical support.
35Week 35: Rapid Weight Gain and Development
This week marks your baby's most rapid weight gain, averaging 8 to 12 ounces per week. Fat accumulates, particularly around the shoulders, while the vernix coating thickens and lanugo hair nearly disappears.
This week marks your baby's most rapid weight gain, averaging 8 to 12 ounces per week. Fat accumulates, particularly around the shoulders, while the vernix coating thickens and lanugo hair nearly disappears.
36Week 36: Ready for Birth
The baby measures approximately 46 cm. It is likely positioned head-down in the pelvis. Lung development accelerates in preparation for birth.
The baby measures approximately 46 cm. It is likely positioned head-down in the pelvis. Lung development accelerates in preparation for birth.
37Week 37: Coordination and Light Sensitivity
Your baby can now grasp with their fingers and may turn toward a bright light shown in the uterus, demonstrating improved coordination.
Your baby can now grasp with their fingers and may turn toward a bright light shown in the uterus, demonstrating improved coordination.
38Week 38: Meconium Formation
Your baby can suck and swallow amniotic fluid, leading to waste buildup in the intestines. This waste, including shed intestinal cells, dead skin cells, and lanugo hair, forms meconium, the greenish-black substance that is your baby's first bowel movement.
Your baby can suck and swallow amniotic fluid, leading to waste buildup in the intestines. This waste, including shed intestinal cells, dead skin cells, and lanugo hair, forms meconium, the greenish-black substance that is your baby's first bowel movement.
39Week 39: Umbilical Cord Details and Immune Support
The umbilical cord typically measures about 22 inches long and 0.5 inches thick. While it can occasionally wrap around the baby's neck, this usually poses no issue unless it compresses during delivery, potentially necessitating a C-section. Most vernix and lanugo have disappeared. Your body has been providing antibodies through the placenta to help your baby's immune system fight infections for the first 6–12 months.
The umbilical cord typically measures about 22 inches long and 0.5 inches thick. While it can occasionally wrap around the baby's neck, this usually poses no issue unless it compresses during delivery, potentially necessitating a C-section. Most vernix and lanugo have disappeared. Your body has been providing antibodies through the placenta to help your baby's immune system fight infections for the first 6–12 months.
40Week 40: Full-Term
At around 51 cm, the baby is fully developed and ready to be born. Labor onset is influenced by a mix of physical, hormonal, and emotional factors.
At around 51 cm, the baby is fully developed and ready to be born. Labor onset is influenced by a mix of physical, hormonal, and emotional factors.
Trimester 1
Trimester 2
Trimester 3
OVERVIEW OF PREGNANCY BY TRIMESTER
- First Trimester (Conception to 12 Weeks)
Early pregnancy symptoms include missed periods, nausea, breast changes, fatigue, and frequent urination. If you suspect pregnancy, taking a test is advisable. Early confirmation allows for timely care and options. Miscarriage is common in this stage, with about 1 in 4 pregnancies ending in miscarriage, primarily within the first 12 weeks. - Second Trimester (13 to 27 Weeks)
During this period, morning sickness typically eases, and energy levels increase. Visible weight gain is normal and important for both mother and baby, but should be managed through a healthy diet and regular exercise. Gestational diabetes is usually screened for between weeks 24 and 28 but can develop earlier. - Third Trimester (28 to 40 Weeks)
The baby grows rapidly, and mothers may experience increased fatigue and physical changes. As the due date approaches, the baby may engage in the pelvis, preparing for birth. Common experiences include anxiety, back pain, breathlessness, and sleep disturbances. There is an elevated risk of preeclampsia during this stage, especially in the latter half of the trimester.
