Pregnancy Calendar: Second Trimester

Months four through six of your pregnancy will mark major fetal growth spurts, resulting in you gaining quite a bit of weight. Weight gain depends on your pre-pregnancy BMI and whether you are having multiples. You could gain anywhere between 11 and 54 pounds throughout your pregnancy. It is important for you to continue your monthly doctor visits, as they will help monitor your baby’s development, screen for diseases, and ensure your delivery will be as complication-free as possible.

13-17 Weeks


Increased sex drive, increased waistline, decreased nausea, detectable baby movements, weight gain, moodiness

Fetal Development

Baby weighs about an ounce and measures about three inches, digestive tract forms, skeleton develops bones, arm and leg movement, thumb sucking; by week 17 baby’s weight and size double

Prenatal Care

See physician once a month

  • Check baby’s heartbeat, changes in weight, test for anemia, continue screening for health risks

Between weeks 15 and 22:

  • Optional screenings and tests offered to all women, but especially encouraged among women:
    • 35 and older
    • With family history of birth and genetic defects
    • Using insulin to treat diabetes
  • Quadruple Screen Test
    • Most accurate between weeks 16 and 18
    • Blood test to determine risks of
      • Down Syndrome
      • Neural Tube Defects
    • Measures risks based on:
      • Levels of four pregnancy hormones
        • Alpha-fetoprotien (AFP) – produced by baby
        • Human Chorionic Gonadotropin (hCG) – produced in placenta
        • Unconjugated Estriol (uE3) – form of estrogen produced in fetus and placenta
        • Inhibin A – released by placenta
      • Mother’s age, ethnic background and weight
      • Baby’s gestational age
    • Screening does not diagnose defects
    • Results of screening may prompt further testing that lead to diagnosis

Causes for Concern

Once you reach the second trimester, your risk of miscarriage is significantly reduced. However, continue to watch for abnormal bleeding, “water breaking,” swelling in your extremities, or headaches. Schedule dental cleanings, since swollen gums and calcium fluctuations can affect the health of your teeth. It is important to maintain dental health and avoid oral infections as they have been linked to preterm births. Talk to your dentist about what procedures are safe for you to undergo during your pregnancy.

18-22 Weeks


Rapid breast growth, continued weight gain, rounding of the belly, weak contractions, stretch marks, waistline growth, gum swelling, joint cramps, back pain

Fetal Development

Taste buds, light and auditory responses, transparent skin, lung activity, hair growth

Prenatal Care

Mid-pregnancy or Second Trimester Ultrasound

  • Takes place around week 20
  • Checks for continued development of organs, limbs, and bodily functions
  • Determines the sex of the baby
  • Measures growth of baby to map progress according to due date
  • Detects defects like:
    • Cleft lip
    • Kidney problems
    • Spina Bifida (defect of the spinal cord)
  • Leads to further tests for:
    • Suspected heart problems
    • Inconclusive results
  • Requires later screening if the baby was in the wrong position

23-27 Weeks


Weight gain (about a pound per week), belly growth, hemorrhoids, continued joint and back pain

Fetal Development

Increased movement, blood cell production, skin becomes opaque, continued hair growth, fingerprints and footprints form, response to sounds; baby’s size likely to have tripled since week 12

Prenatal Care

Diabetes blood screening

  • Take place between weeks 24 and 28
  • Check for signs of gestational diabetes
    • High blood sugar condition only developed during pregnancy
  • Not a diagnostic screening
    • Results can lead to further testing
  • Gestational Diabetes can adversely affect:
    • Mother’s chances of cesarean, a difficult labor, depression, or type 2 diabetes following the birth
    • Child’s chances of hypoglycemia or jaundice

Continued lab tests necessary if:

  • Screenings done earlier in the trimester were:
    • Inconclusive
    • False positives
  • Family history of birth and genetic defects
  • Mother is treating a chronic illness
  • Monthly ultrasounds and checkups show developments aren’t where they should be
    • Signs of developmental issues in earlier ultrasounds monitored
    • Further tests administered to check for causes of underdevelopment
  • Fetal movement checks