Nucleotides and the double helix. DNA, or deoxyribonucleic acid, is the heritable material found in all cells. DNA provides the instructions to build, maintain, and regulate cells and organisms and is passed on when cells divide and when organisms reproduce.
Calculating Conception. Gestational age, or the age of the baby, is calculated from the first day of the motherâs last menstrual period.Since the exact date of conception is almost never known, the first day of the last menstrual period is used to measure how old the baby is. Use our Pregnancy Calculator to calculate these dates for you.he baby can be measured as early as 5 or 6 weeks after the motherâs last menstrual period. Measuring the baby using ultrasound is most accurate in early pregnancy. It becomes less accurate later in pregnancy. The best time to estimate gestational age using ultrasound is between the 8th and 18th weeks of pregnancy.
1 Calculating the gestational age from the conception date is more accurate. 2  It is the preferred way of the medical textbooks. 3  How far along you are in your pregnancy (from the first day of the last menstrual cycle). 4  Calculating the gestational age from the from the first day of the last menstrual cycle is more practical. Sperm lives for about 2 days. Because of the uncertainly of the exact conception date, obstetricians prefer to calculate the fetal age from the first day of the last menstrual cycle.