Protocol - Gestational Age - Maternal Interview

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Extremely Low Gestational Age Newborns (ELGAN) Study, Maternal Interview


Publicly available


Twelve questions about whether the woman was trying to get pregnant or had infertility treatment; dates for the last menstrual cycle, first prenatal visit and first ultrasound, and estimates of the delivery date.


Now I’d like your help to accurately determine your baby’s gestational age.

1. Were you trying to get pregnant when you did?

[ ] 0 No

[ ] 1 Yes

2. Were you regularly using any form of birth control when you got pregnant?

[ ] 0 No

[ ] 1 Yes

3. If NO: For how many months were you having sex without using any birth control? __ __ __

4. Did you have any kind of infertility therapy to get pregnant this time?

[ ] 0 No

[ ] 1 Yes

5. If YES: Were you treated with:

a. Intrauterine insemination (IUI)

[ ] 0 No

[ ] 1 Yes

b. A fertility drug such as Clomiphene (Clomid) or Perganol

[ ] 0 No

[ ] 1 Yes

c. A procedure such as IVF or ICSI

[ ] 0 No

[ ] 1 Yes

6. IF Q5b is YES: What drugs were you treated with?

[ ] 1. Clomid, Serophene (Clomiphene)

[ ] 2. Gonal-F, Follistim

[ ] 3. Pergonal, Repronex, Humogon

[ ] 4. Fertinex

[ ] 5. Pregnyl, Profasi, Novarelle, Ovidrel

[ ] 6. Lupron

[ ] 7. Progesterone, Utrogestan, Prometrium, Crinone

[ ] 8. Other

7. IF Q5c is YES: What fertility procedure was used?

[ ] 1 IVF (in vitro fertilization). Fertilization takes place in a Petri dish and the embryo transferred to the uterus.

[ ] 2 IVF+ assisted hatching. Same as 1 except the layer of cells covering the egg (zona pellucida) is removed permitting easier and earlier cell division in the embryo.

[ ] 3 GIFT (gamete intra fallopian transfer). Sperm and egg are injected into the fallopian tube where fertilization takes place.

[ ] 4 ZIFT (zygote intra fallopian transfer). Fertilization takes place in a Petri dish and the embryo transferred to the fallopian tube.

[ ] 5 ICSI (intra cytoplasmic sperm injection). Sperm are injected into the cytoplasm of the egg and the resulting embryo transferred to the uterus.

[ ] 6 ICSI + assisted hatching. Same as 5 except the zona pellucida is removed.

8. What was your transfer date (mmm/dd/yyyy)? __ __ __/__ __/ 20 __ __

All dates are entered in a standard mmm/dd/yyyyy format. The ’mmm’ is for the first three characters of the month (jan, feb, mar, apr, may, jun, jul, aug, sep, oct, nov, dec). You need not capitalize. The ’dd’ is for the two digits that represent the day in the month. The ’yyyyy’ part is the four digits that represent the year.

9. What was your retrieval date (mmm/dd/yyyy)? __ __ __/__ __/ 20 __ __

10. How many eggs were retrieved? __ __

11. When did your last entirely normal period begin (mmm/dd/yyyy)? __ __ __/__ __/ 20 __ __

If the woman is uncertain about what and/or when was the last menstrual period, repeat the question slowly and allow her to make her own decision about it. If she answers ’Well, I thought it was one date but my doctor thought it was another,’ let the woman know that you want what she thought was the first day of her LMP. We will get the doctor’s perception from the medical record.

12. When did you first go to a doctor or clinic for prenatal care (mmm/dd/yyyy or week of pregnancy)? __ __ __/__ __/ 20 __ __

Please enter the date (mmm/dd/yyyy) the woman first visited a doctor or clinic for prenatal care. For the women who had fertility therapy, the date of the first prenatal care visit is the date when the pregnancy was confirmed. If a woman has any trouble with this question, again, repeat it slowly and emphasize the underlined word. If she can’t recall the exact date of her first prenatal visit ask her the week of pregnancy in which she first saw the doctor. If the woman did not receive services specifically for pregnancy care, enter 0 for week in pregnancy.

13. What due date were you given then (mmm/dd/yyyy)? __ __ __/__ __/ 20 __ __

14. When was your first ultrasound performed? (mmm/dd/yyyy or week of pregnancy) __ __ __/__ __/ 20 __ __

15. Did the ultrasound give the same due date as your doctor or nurse?

[ ] 0 No

[ ] 1 Yes

16. If NO: What date did the ultrasound give (mmm/dd/yyyy)? __ __ __/__ __/ 2 0 __ __

17. Did anyone ever change your due date?

[ ] 0 No

[ ] 1 Yes

18. If YES: Why?

[ ] 1 baby was too small

[ ] 2 baby was too big

[ ] 3 other

19. What was the final due date (mmm/dd/yyyy)? __ __ __/__ __/ 20 __ __

Use the "last" due date. If the due date was changed following the sonogram, use that due date. If it was not changed, then use the initial due date.

Then calculate the days before or after the due date that the baby was actually born. The formula is

Gestational age at birth = 280 + (date of birth-due date).

So if a baby was born before the due date then the gestational age will be <280, and if it was born after the due date it will be >280. 280 days from the first day of the LMP is the ‘idealized length’ of human pregnancy.

Personnel and Training Required

The interviewer must be trained to conduct personal interviews with individuals from the general population. The interviewer must be trained and found to be competent (i.e., tested by an expert) at the completion of personal interviews. The interviewer should be trained to prompt respondents further if a "don’t know" response is provided.

Equipment Needs



Requirement CategoryRequired
Average time of greater than 15 minutes in an unaffected individualNo
Major equipmentNo
Specialized requirements for biospecimen collectionNo
Specialized trainingNo

Mode of Administration


Life Stage:

Adult, Pregnancy

Specific Instructions:

Accuracy of gestational age (GA) is essential to the validity of numerous pregnancy and birth outcomes. This interview should be completed at initial stages of data collection/patient contact. The interview should be completed at or after the time of delivery in order to determine the gestational age at delivery. Objective determination (Gestational Age - Medical Record Abstraction) is preferred to maternal recall given inherent risk of bias in the latter. Although these items are from a study of extremely low gestational age newborns, the PhenX Pregnancy Work Group members recommend it for use with any newborn.

Research Domain Information

Release Date:

January 31, 2017


The period of time in weeks and days from the first day of the last menstrual period to the estimated date of delivery.


Gestational age is an essential component of research on pregnancy outcomes. It is often used in research for stratification purposes, influences interpretation of many related measures, and is inversely associated with many neonatal complications.

Selection Rationale

This protocol is from the well-established Extremely Low Gestational Age Newborns (ELGAN) Research Study which is a large scale multicenter epidemiologic study.




Common Data Elements (CDE)Pregnancy Gestational Age Assessment Questionnaire Assessment Text5633779CDE Browser

Process and Review

The Expert Review Panel has not reviewed this measure yet.


Boston Medical Center, Extremely Low Gestational Age Newborns (ELGAN) Study, 2002 Maternal Interview, Items 25-43

General References

McElrath, T. F., Hecht, J. L., Dammann, O., Boggess, K., Onderdonk, A., Markenson, G., Harper, M., Delapapa, E., Leviton, A. (2008). Pregnancy disorders that lead to delivery before the 28th week of gestation: An epidemiologic approach to classification. American Journal of Epidemiology, 168(9), 980-989.

O’Shea, T. M., Allred, E. N., Dammann, O., Hirtz, D., Kuban, K. C., Paneth, N., & Leviton, A. (2009). The ELGAN study of the brain and related disorders in extremely low gestational age newborns. Early Human Development, 85(11), 719-725.

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