Pregnancy Guide: Symptoms, Trimesters, and Due Dates
Author: Disabled World (DW)
Updated/Revised Date: 3 Aug 2026
Table of Contents:
Synopsis - Definition - About This Section - FAQs - Publications - Subtopics
Synopsis
A factual guide to pregnancy covering early symptoms, the three trimesters, fetal development week by week, conception, and estimating your baby's due date.
At a Glance
- 1 - Childbirth usually occurs about 38 weeks after conception.
- 2 - Babies can see up to about two feet away at birth and are born with sucking and grasping reflexes.
- 3 - Infants born in the 37th and 38th weeks, once called full term, are now classed as early term and face more health risks.
- 4 - In women with a short cervix carrying twins, progestogen hormones reduced the risk of preterm birth by 50 percent, according to a University of Adelaide review.
Topic Definition
- Pregnancy
Pregnancy, also called gestation, is the period during which one or more offspring develop as an embryo or fetus inside a woman's uterus, beginning at conception when a sperm fertilizes an egg. It typically lasts about forty weeks from the last menstrual period and is divided into three trimesters, each marked by distinct physical changes in the mother and developmental milestones in the growing baby. Throughout this time the placenta supplies the fetus with nutrients and oxygen, while regular prenatal care helps protect the health of both mother and child from the earliest weeks right through to delivery.
Overview
In human reproduction, pregnancy (or gestation) is the development of one or more offspring, known as an embryo or fetus, in the uterus of a woman. A multiple pregnancy involves more than one embryo or fetus in a single pregnancy, such as with twins. Childbirth usually occurs about 38 weeks after conception.
Healthy pregnancies start before a mother becomes pregnant, even before they consider motherhood.
Women may benefit from basic pre-pregnancy planning and regular visits with their health care provider. Prenatal care visits are important to both the baby and the mother. There are some things that a mother might do when they are pregnant that could harm their baby, to include drinking or smoking. Certain medications may also be a problem, including ones that a doctor has prescribed. It is essential to eat a healthy diet and drink plenty of fluids. Early in the pregnancy, a mother might experience nausea or morning sickness, or need more rest.
Trimesters
The average pregnancy lasts approximately forty weeks, grouped into three trimesters.
1st Trimester
During the first trimester, a mother's body experiences several changes. A mother's hormones change and affect nearly every organ system in their body. The changes may initiate symptoms, even in the first weeks of the pregnancy.
First Trimester (Week 1 to Week 12):
- The events that lead to pregnancy begin with conception, in which the sperm penetrates the egg produced by an ovary.
- The zygote (fertilized egg) then travels through the woman's fallopian tube to the uterus, where it implants itself in the uterine wall. The zygote is made up of a cluster of cells formed from the egg and sperm. These cells form the fetus and the placenta. The placenta provides nutrients and oxygen to the fetus.
2nd Trimester
The majority of women feel the second trimester of pregnancy is easier than the first one. It is important to remain informed about pregnancy during this trimester. A mother may notice symptoms such as fatigue and nausea are not disappearing and new, more noticeable changes to their body are occurring. A mother's abdomen will expand as their baby grows; before the second trimester is over, they will feel their baby starting to move.
Second Trimester (Week 13 to Week 28):
- At 16 weeks, and sometimes as early as 12 weeks, a woman can typically find out the sex of her infant. Muscle tissue, bone, and skin have formed.
- At 20 weeks, a woman may begin to feel movement.
- At 24 weeks, footprints, and fingerprints have formed and the fetus sleeps and wakes regularly.
- According to research from the NICHD Neonatal Research Network, the survival rate for babies born at 28 weeks was 92%, although those born at this time will likely still experience serious health complications, including respiratory and heart problems.
3rd Trimester
The third trimester may bring some of the same discomforts a mother experienced during the second trimester.
In addition, many women can find it more difficult to breathe and notice they have to use the bathroom more often because their baby is getting bigger and placing more pressure on their organs. Not to worry, the baby is fine, and these issues will lessen after the baby is born.
Third Trimester (Week 29 to Week 40):
- At 32 weeks, the bones are soft and yet almost fully formed, and the eyes can open and close.
- Infants born before 37 weeks are considered preterm. These children are at increased risk for concerns such as developmental delays, vision and hearing issues, and cerebral palsy. According to the March of Dimes, as many as 70% of preterm births occur between 34 and 36 weeks - these are late-preterm births.
- Infants born in the 37th and 38th weeks of pregnancy - previously considered full term - are now considered "early term." These infants face more health risks than infants who are born at 39 weeks or later, which is now considered full term.
- Infants born at 39 or 40 weeks of pregnancy are considered full term. Full-term infants have better health outcomes than do infants born earlier or, in some cases, later than this period. Therefore, if the mother and baby are healthy, it is best to deliver at or after 39 weeks to give the infant's lungs, brain, and liver time to fully develop.
- Infants born at 41 weeks through 41 weeks and 6 days are considered late term.
- Infants who are born at 42 weeks and beyond are considered post term.
Signs and Symptoms of pregnancy Include:
- Nausea or vomiting, morning sickness
- Sore breasts or nipples
- Fatigue
- Headaches
- Food cravings or aversions
- Mood swings
- Frequent urination
Things you can do include pursing education related to:
- Circumcision
- Baby furniture
- Breastfeeding
- Birthing and parenting
- Making your home safe
- Health care for your baby
As the due date approaches, look for any sign that labor is about to begin, no matter how small. Mothers may notice their baby has dropped, or moved into the lower part of their pelvis. A pelvic exam during a prenatal visit to a doctor can reveal changes to a mother's cervix they might not feel, yet suggest their body is getting ready.
Once the baby is born, spend the first hours of the baby's life letting your baby know your voice and study your face. The baby can see up to about two feet away. Babies are born with sucking and grasping reflexes; put your finger in the baby's palm. Feed your baby when they show signs of hunger.
Halving Risk of Pre-term Birth for Some Twin Pregnancies
A study, involving researchers from the University of Adelaide's Robinson Research Institute, reviewed all the previous large studies conducted into the use of progestogen hormones, which have been trialed over the past 10 years to help prevent preterm birth in twins. The results, published in BJOG: An International Journal of Obstetrics and Gynecology, show that an important discovery had been missed in each of those previous studies.
Until now, the research has demonstrated that there has been no benefit from the use of progestogen hormones in preventing preterm birth for women with a twin pregnancy. Thanks to this international review, we can now see that there is a very specific benefit to one group of high-risk pregnancies: women who have a short cervix, who are pregnant with twins.
Twin pregnancies are very much at risk of preterm birth, with half of these pregnancies delivering before 37 weeks gestation. For women with a short cervix who are also pregnant with twins, this is what I would call a super high-risk category for adverse outcomes, either for infant death or for serious health problems after birth. We found that by using progestogen hormones, there was a 50% reduction in risk of preterm birth for this group of pregnancies.
Pregnancy Facts and Statistics
- In Europe, the average childbearing age has been rising continuously for some time.
- In Western, Northern, and Southern Europe, first-time mothers are on average 26 to 29 years old, up from 23 to 25 years at the start of the 1970s.
- The total fertility rate (TFR) in 2013 was estimated to be highest in Niger (7.03 children born per woman) and lowest in Singapore (0.79 children/woman).
- The incidence of pregnancy among the female population, as well as the ages at which it occurs, differ significantly by country and region, and are often influenced by a multitude of factors, such as cultural, social and religious norms; access to contraception; and the prevalence of (higher) education.
- In some European countries (Spain), the mean age of women at first childbirth has now even crossed the 30-year threshold. This process is not restricted to Europe. Asia, Japan, and the United States are all seeing average age at first birth on the rise, and increasingly the process is spreading to countries in the developing world like China, Turkey, and Iran. In the US, the age of first childbirth was 25.4 in 2010.
Motherhood is one of life's greatest responsibilities and joys. By doing everything you can to prepare for parenthood now, before your baby is born, the transition to parenthood can be a lot easier.
Frequently Asked Questions
How soon can a pregnancy test detect pregnancy
Most home pregnancy tests can detect the hormone hCG from the first day of a missed period, though some sensitive tests may give a result a few days earlier.
What foods should be avoided during pregnancy
Common foods to avoid include raw or undercooked meat and eggs, unpasteurized dairy, high-mercury fish such as swordfish, deli meats unless heated, and alcohol.
How much weight should a woman gain during pregnancy
Recommended weight gain varies by starting weight, but for a woman of average weight carrying one baby it is often around 25 to 35 pounds across the whole pregnancy.
Is it safe to exercise while pregnant
For most healthy pregnancies moderate activity such as walking, swimming, or prenatal yoga is encouraged, but a health care provider should confirm what is safe for you.
How is a due date calculated
A due date is usually estimated at 40 weeks from the first day of the last menstrual period, or it can be based on ultrasound measurements of the baby.
What is the difference between an embryo and a fetus
The developing baby is called an embryo during the first eight weeks after conception and a fetus from the ninth week until birth.
Can you feel the baby move in the first trimester
Most women do not feel movement in the first trimester, with first flutters typically noticed around 20 weeks or sometimes a little earlier in later pregnancies.
Curated and edited by Ian C. Langtree, Founder & Editor-in-Chief, Disabled World. This section is maintained by the Disabled World editorial team.
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