How to use the Time Window Calculator ?

 

    

Provide pregnancy dating and then click the "Calculate Test Date" button. Time Windows will be provided for drawing the First and Second trimester blood specimens and for obtaining a Nuchal Translucency Ultrasound. Use the radio buttons to select dating fields. Use calendar icon to select a date.

California Prenatal Screening Program

Time Windows for Prenatal Screening Tests

 

 Patient Name :
   

Today's Date :
Select and enter one dating method (in the following order of preference):

Enter Date of ultrasound : Pick a date
  Enter CRL mm   (Valid range for CRL dating is 9.5 - 84.5 mm)
  Enter gestational age on ultrasound date: Weeks   Days (0-6 days)
Enter first day of last menstrual period: Pick a date
Enter date of physical exam: Pick a date
  Enter gestational age on exam date:   Weeks  
       

First Trimester Blood Specimen Time Window

 

 10 Weeks 0 Days

         13 Weeks 6 Days
First trimester blood specimen  should be drawn between:

and
Draw a First Trimester blood specimen between 10 weeks 0 days and 13 weeks 6 days of pregnancy, using the California Program’s First Trimester Screening Lab test form (Blue border).
Nuchal Translucency (NT) Ultrasound Time Window
 

 11 Weeks 2 Days

         14 Weeks 2 Days
Nuchal translucency ultrasound should be done between:

and
If you choose to have an NT ultrasound, schedule the NT appointment between 11 weeks 2 days and 14 weeks 2 days of pregnancy.
Second Trimester Blood Specimen Time Window
 

 15 Weeks 0 Days

        20 Weeks 0 Days
Second trimester blood specimen should be drawn between:

and
Draw a Second Trimester blood specimen between 15 weeks 0 days and 20 weeks 0 days of pregnancy, using the California Program’s Second Trimester Screening Lab test form (Green border).

Note: Your browser must be Java-enabled for the calculator to work. The calculations are estimates based on the pregnancy dating provided. Patients should consult their clinician about prenatal screening.