This calculator is only to be used only as a guide and when calulating via LMP assumes that your menstual cycle is 28 days long. This tool does not replace the advice of your consultant/clinic
Week 1 - 2 of pregnancy *note- Although you are not actually pregnant at this point, pregnancy is always taken from the first day of your last LMP or 2 weeks before EC so, by the time you have EC, you will already have been pregant 2 weeks.
The egg is fertalised and forms a zygote which then undergoes a process known as cleavage. A hollow cavity forms marking the blastocyst stage The blastocyst hatches from its protein shell (zona pellucida) and implants onto the endometrial lining of the mothers uterus. If separation into identical twins occurs, 1/3 of the time it will happen before day 5.
The blastocyst is fully implanted day 7-12 of fertilisation Formation of the yolk sac. If separation into identical twins occurs, 2/3 of the time it will happen between days 5 and 9. If it happens after day 9, there is a significant risk of the twins being conjoined.
A neural groove (future spinal cord) forms. Primitive heart tube is forming. (day 20 of fertilisation.)
The embryo measures 4 mm (1/8 inch) in length and begins to curve into a C shape. The heart bulges, further develops, and begins to beat in a regular rhythm. Branchial arches, grooves which will form structures of the face and neck, form. The ears begin to form as otic pits. Arm buds and a tail are visible. The first traits of the lung appear. The first traits of the liver appear. Buccopharyngeal membrane ruptures. This is the future mouth. Cystic diverticulum, which will become the gallbladder, and dorsal pancreatic bud, which will become the pancreas appear. Urorectal septum begins to form. Thus, the rectal and urinary passageways become separated. Spleen appears. Ureteric buds appear.
The embryo measures 8 mm (1/4 inch) in length. Lens pits and optic cups form the start of the developing eye. Nasal pits form. The brain divides into 5 vesicles, including the early telencephalon. Leg buds form and hands form as flat paddles on the arms. Rudimentary blood moves through primitive vessels.
The embryo measures 13 mm (1/2 inch) in length. Lungs begin to form. The brain continues to develop. Arms and legs have lengthened with foot and hand areas distinguishable. The hands and feet have digits, but may still be webbed.
The embryo measures 18 mm (3/4 inch) in length. Nipples and hair follicles begin to form. Location of the elbows and toes are visible. Spontaneous limb movements may be detected by ultrasound. All essential organs have at least begun formation.
Since the precursors of all the major organs are created by this time, the fetal period is described both by organ and by a list of changes by weeks of gestational age. Because the precursors of the organs are formed, fetus also is not as sensitive to damage from environmental exposures as the embryo. Instead, toxic exposures often cause physiological abnormalities or minor congenital malformation From the 8th week until birth (around 38 weeks), the developing organism is called a fetus. The fetus is not as sensitive to damage from environmental exposures as the embryo, and toxic exposures often cause physiological abnormalities or minor congenital malformation. All major structures are already formed in the fetus, but they continue to grow and develop.
Embryo measures 30 mm (1.2 inches) in length. Intestines rotate. Facial features continue to develop. The eyelids are more developed. The external features of the ear begin to take their final shape.
The fetus reaches a length of about 15 cm (6 inches). A fine hair called lanugo develops on the head. Fetal skin is almost transparent. More muscle tissue and bones have developed, and the bones become harder. The fetus makes active movements. Sucking motions are made with the mouth.
The fetus reaches a length of 20 cm (8 inches). Lanugo covers the entire body. Eyebrows and eyelashes appear. Nails appear on fingers and toes. The fetus is more active with increased muscle development. "Quickening" usually occurs (the mother can feel the fetus moving). The fetal heartbeat can be heard with a stethoscope.
The fetus reaches a length of 28 cm (11.2 inches). The fetus weighs about 725 g (1 lb 10 oz). Eyebrows and eyelashes are well formed. All of the eye components are developed. The fetus has a hand and startle reflex. Footprints and fingerprints continue forming. Air sacs are forming in lungs.
The fetus reaches a length of 38 cm (15 inches). The fetus weighs about 1.2 kg (2 lb 11 oz). The brain develops rapidly. The nervous system develops enough to control some body functions. The eyelids open and close. he respiratory system, while immature, has developed to the point where gas exchange is possible. A baby born prematurely at this time may survive.
The fetus reaches a length of about 38-43 cm (15-17 inches). The fetus weighs about 2 kg (4 lb 6 oz). The amount of body fat rapidly increases. Rhythmic breathing movements occur, but lungs are not fully mature. Thalamic brain connections, which mediate sensory input, form. Bones are fully developed, but are still soft and pliable.
The fetus reaches a length of about 40-48 cm (16-19 inches). The fetus weighs about 2.5 to 3 kg (5 lb 12 oz to 6 lb 12 oz). Body fat increases. Fingernails reach the end of the fingertips. A baby born at 36 weeks has a high chance of survival, but may require medical interventions.
The fetus is considered full-term at the 37th week of gestational age. It may be 48 to 53 cm (19 to 21 inches) in length. Fingernails extend beyond fingertips. Small breast buds are present on both sexes. Head hair is now coarse and thickest.
Heartbeat May Be Detected by Ultrasound
Brainwaves Begin
Essential Structures Complete
Movement Begins
Fetus May Suck Thumb
Maternal Sounds Recognized by Fetus
