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Identifying Pregnancy Start and End Dates

identifying_pregnancy_start_and_end_dates.Rmd

Identifying Pregnancy Start and End Dates

The following logic will calculate the start and end dates of a pregnancy. If patients have multiple outcomes, gestation weeks codes or multiple trimester codes, overlapping start and end dates can result. This step applies hierarchies to assign start and end dates to each pregnancy episode for each patient.

Section A – Estimating the start and end dates of a pregnancy using the outcomes, gestation weeks and trimester codes

  1. Using ICD-10 codes Z3Axx and P073xx/P072xx and ICD-9 codes 765.2x to identify the gestation weeks and calculate the start of the pregnancy. If multiple codes occur for the same patients, use the latest claim date and max # of gestation weeks
Code Description Days
P0722 Extreme immaturity of newborn, gestational age 23 completed weeks 161
P0723 Extreme immaturity of newborn, gestational age 24 completed weeks 168
P0724 Extreme immaturity of newborn, gestational age 25 completed weeks 175
P0725 Extreme immaturity of newborn, gestational age 26 completed weeks 182
P0726 Extreme immaturity of newborn, gestational age 27 completed weeks 189
P0731 Preterm newborn, gestational age 28 completed weeks 196
P0732 Preterm newborn, gestational age 29 completed weeks 203
P0733 Preterm newborn, gestational age 30 completed weeks 210
P0734 Preterm newborn, gestational age 31 completed weeks 217
P0735 Preterm newborn, gestational age 32 completed weeks 224
P0736 Preterm newborn, gestational age 33 completed weeks 231
P0737 Preterm newborn, gestational age 34 completed weeks 238
P0738 Preterm newborn, gestational age 35 completed weeks 245
P0739 Preterm newborn, gestational age 36 completed weeks 252
Z3A08 8 weeks gestation of pregnancy 56
Z3A09 9 weeks gestation of pregnancy 63
Z3A10 10 weeks gestation of pregnancy 70
Z3A11 11 weeks gestation of pregnancy 77
Z3A12 12 weeks gestation of pregnancy 84
Z3A13 13 weeks gestation of pregnancy 91
Z3A14 14 weeks gestation of pregnancy 98
Z3A15 15 weeks gestation of pregnancy 105
Z3A16 16 weeks gestation of pregnancy 112
Z3A17 17 weeks gestation of pregnancy 119
Z3A18 18 weeks gestation of pregnancy 126
Z3A19 19 weeks gestation of pregnancy 133
Z3A20 20 weeks gestation of pregnancy 140
Z3A21 21 weeks gestation of pregnancy 147
Z3A22 22 weeks gestation of pregnancy 154
Z3A23 23 weeks gestation of pregnancy 161
Z3A24 24 weeks gestation of pregnancy 168
Z3A25 25 weeks gestation of pregnancy 175
Z3A26 26 weeks gestation of pregnancy 182
Z3A27 27 weeks gestation of pregnancy 189
Z3A28 28 weeks gestation of pregnancy 196
Z3A29 29 weeks gestation of pregnancy 203
Z3A30 30 weeks gestation of pregnancy 210
Z3A31 31 weeks gestation of pregnancy 217
Z3A32 32 weeks gestation of pregnancy 224
Z3A33 33 weeks gestation of pregnancy 231
Z3A34 34 weeks gestation of pregnancy 238
Z3A35 35 weeks gestation of pregnancy 245
Z3A36 36 weeks gestation of pregnancy 252
Z3A37 37 weeks gestation of pregnancy 259
Z3A38 38 weeks gestation of pregnancy 266
Z3A39 39 weeks gestation of pregnancy 273
Z3A40 40 weeks gestation of pregnancy 280
Z3A41 41 weeks gestation of pregnancy 287
Z3A42 42 weeks gestation of pregnancy 294
Z3A49 Greater than 42 weeks gestation of pregnancy 301
765.22 24 completed weeks of gestation 168
765.23 25-26 completed weeks of gestation 182
765.24 27-28 completed weeks of gestation 196
765.25 29-30 completed weeks of gestation 210
765.26 31-32 completed weeks of gestation 224
765.27 33-34 completed weeks of gestation 238
765.28 35-36 completed weeks of gestation 252

  1. Using the codes that are specific to preterm delivery and trimester. Use the trimesters to calculate the start and end dates of the pregnancy

    • Trimester 3 (assigning median of 34 weeks)

      1. Use the last claim date

      2. Pregnancy end date = the last claim date

      3. Pregnancy start date = the last claim date - 238

    • Trimester 2 (assigning median of 26 weeks)

      1. Use the last claim date

      2. Pregnancy end date = the last claim date

      3. Pregnancy start date = the last claim date - 182

O6012 Preterm labor second tri w preterm delivery second trimester
O6012X0 Preterm labor second tri w preterm delivery second tri| unsp
O6012X1 Preterm labor second tri w preterm del second tri| fetus 1
O6012X2 Preterm labor second tri w preterm del second tri| fetus 2
O6012X3 Preterm labor second tri w preterm del second tri| fetus 3
O6012X4 Preterm labor second tri w preterm del second tri| fetus 4
O6012X5 Preterm labor second tri w preterm del second tri| fetus 5
O6012X9 Preterm labor second tri w preterm delivery second tri| oth
O6013 Preterm labor second tri w preterm delivery third trimester
O6013X0 Preterm labor second tri w preterm delivery third tri| unsp
O6013X1 Preterm labor second tri w preterm del third tri| fetus 1
O6013X2 Preterm labor second tri w preterm del third tri| fetus 2
O6013X3 Preterm labor second tri w preterm del third tri| fetus 3
O6013X4 Preterm labor second tri w preterm del third tri| fetus 4
O6013X5 Preterm labor second tri w preterm del third tri| fetus 5
O6013X9 Preterm labor second tri w preterm delivery third tri| oth
O6014 Preterm labor third tri w preterm delivery third trimester
O6014X0 Preterm labor third tri w preterm delivery third tri| unsp
O6014X1 Preterm labor third tri w preterm del third tri| fetus 1
O6014X2 Preterm labor third tri w preterm del third tri| fetus 2
O6014X3 Preterm labor third tri w preterm del third tri| fetus 3
O6014X4 Preterm labor third tri w preterm del third tri| fetus 4
O6014X5 Preterm labor third tri w preterm del third tri| fetus 5
O6014X9 Preterm labor third tri w preterm delivery third tri| oth

  1. Using the following outcome codes to calculate the start and end dates of the pregnancy.(assuming 270 is 39 weeks of pregnancy)

    • Ectopic pregnancy

      1. Use the last claim date

      2. Pregnancy end date = the last claim date

      3. Pregnancy start date = the last claim date - 56

    • Induced/Spontaneous abortion (84 days=12 weeks (mid range of SA/IA diagnosis 6 weeks to 22 weeks) from 0 to 154 days (10 weeks)

      1. Use the last claim date

      2. Pregnancy end date = the last claim date

      3. Pregnancy start date = the last claim date - 70

    • Stillbirth (22-40 weeks) (155 to 280 days) (distribution of data shows median: 189 days and mean 194 days)

      1. Use the last claim date

      2. Pregnancy end date = the last claim date

      3. Pregnancy start date = the last claim date - 194

    • Preterm (24 weeks-37 weeks) within 168-258 (median 34 weeks)

      1. Use the last claim date

      2. Pregnancy end date = the last claim date

      3. Pregnancy start date = the last claim date - 238

    • Cesarean section/Delivery/Post-term birth/Post-term birth*/Term birth 259-280 days

      1. Use the last claim date

      2. Pregnancy end date = the last claim date

      3. Pregnancy start date = the last claim date - 270

    • Unclassified pregnancy loss

      1. Use the last claim date

      2. Pregnancy end date = the last claim date

      3. Pregnancy start date = the last claim date - 70

    • Postpartum

      1. Use the first claim date

      2. Pregnancy end date = the first claim date

      3. Pregnancy start date = the first claim date - 270

  2. Using the trimester codes to calculate the start and end dates of the pregnancy

    • Trimester 3

      1. Use the last claim date

      2. Pregnancy end date = the last claim date

      3. Pregnancy start date = the last claim date - 270

    • Trimester 2

      1. Use the last claim date

      2. Pregnancy end date = the last claim date + 135

      3. Pregnancy start date = the last claim date - 135

    • Trimester 1

      1. Use the first claim date

      2. Pregnancy end date = the first claim date + 214

      3. Pregnancy start date = the first claim date – 56

    • Trimester 4

      1. Use the last claim date

      2. Pregnancy end date = the last claim date + 174

      3. Pregnancy start date = the last claim date – 96

    • Trimester 5

      1. Use the last claim date

      2. Pregnancy end date = the last claim date + 68

      3. Pregnancy start date = the last claim date - 202

    • Trimester 8

      1. Use the first claim date

      2. Pregnancy end date = the first claim date

      3. Pregnancy start date = the first claim date – 270

Performance: Can Assign 98.2% of Pregnancy Claims with a Start & End date

Section B – If patient has overlapping start and end dates during the same pregnancy term, use the following hierarchy logic to assign the correct range.

Start Dates:

  1. If exist, use gestation weeks code start date (i.e. Z3Axx/P073xx/P072xx/765.2x)

  2. If no gestation weeks codes but delivery outcome and classified loss outcome exist, use the following:

    1. Use preterm start date

    2. Use stillbirth start date

    3. Use abortion start date

    4. Use ectopic start date

  3. If no gestation weeks codes and no delivery outcome exist but classified loss outcome exist, use the following:

    1. Use ectopic start date

    2. Use abortion start date

    3. Use stillbirth start date

    4. Use preterm start date

  4. For all remaining case, use the following hierarchy:

    1. Use delivery start date

    2. Use unclassified loss start date

    3. Use trimester 1 start date

    4. Use trimester 2 start date

    5. Use trimester 3 start date

    6. Use trimester 4 start date

    7. Use trimester 5 start date

    8. Use postpartum start date

    9. Use trimester 8 start date

End Dates:

  1. If delivery outcome exists, use delivery end date

  2. If no delivery outcome but gestation weeks exist, use the following:

    1. If gestation weeks last date > ectopic last date, use gestation weeks last date

      If gestation weeks last date <= ectopic last date, use ectopic last date

    2. If gestation weeks last date > abortion last date, use gestation weeks last date

      If gestation weeks last date <= abortion last date, use abortion last date

    3. If gestation weeks last date > stillbirth last date, use gestation weeks last date If gestation weeks last date <= stillbirth last date, use stillbirth last date

    4. If gestation weeks last date > unclassified loss last date, use gestation weeks last date

      If gestation weeks last date <= unclassified loss last date, use unclassified loss last date

    5. If gestation weeks last date > preterm last date, use gestation weeks last date

      If gestation weeks last date <= preterm last date, use preterm last date

    6. If gestation weeks last date > trimester 3 last date, use gestation weeks last date

      If gestation weeks last date <= trimester 3 last date, use trimester 3 last date

    7. If gestation weeks last date > trimester 2 last date, use gestation weeks last date If gestation weeks last date <= trimester 2 last date, use trimester 2 last date

    8. If gestation weeks last date > trimester 1 last date, use gestation weeks last date If gestation weeks last date <= trimester 1 last date, use trimester 1 last date

    9. If gestation weeks last date > trimester 4 last date, use gestation weeks last date

      If gestation weeks last date <= trimester 4 last date, use trimester 4 last date

    10. If gestation weeks last date > trimester 5 last date, use gestation weeks last date

      If gestation weeks last date <= trimester 5 last date, use trimester 5 last date

    11. If gestation weeks last date > postpartum last date, use gestation weeks last date

      If gestation weeks last date <= postpartum last date, use postpartum last date

    12. If gestation weeks last date > trimester 8 last date, use gestation weeks last date If gestation weeks last date <= trimester 8 last date, use trimester 8 last date

  3. If no gestation weeks codes and no delivery outcome exist but classified loss outcome exist, use the following:

    1. Use ectopic last date

    2. Use abortion last date

    3. Use stillbirth last date

    4. Use unclassified loss last date

    5. Use preterm last date

  4. For all remaining case, use the following hierarchy:

    1. Use delivery last date

    2. Use trimester 3 last date

    3. Use trimester 2 last date

    4. Use trimester 1 last date

    5. Use trimester 4 last date

    6. Use trimester 5 last date

    7. Use postpartum last date

    8. Use trimester 8 last date

    9. Use gestation weeks last date

References for estimated duration of pregnancy based on loss outcomes:

Ectopic pregnancy is usually diagnosed in the first trimester of pregnancy. The most common gestational age at diagnosis is 6 to 10 weeks. Average 7.2 weeks. (Murray H, Baakdah H, Bardell T, Tulandi T. Diagnosis and treatment of ectopic pregnancy. CMAJ : Canadian Medical Association Journal. 2005;173(8):905-912. doi:10.1503/cmaj.050222.)

Spontaneous Abortion occurs at a mean gestational age of 9.751 (SD 4.738) weeks. Lang K, Nuevo-Chiquero A. Trends in Self-reported Spontaneous Abortions: 1970–2000. Demography. 2012;49(3):989-1009. doi:10.1007/s13524-012-0113-0.

Induced Abortions occur in the first 12 weeks for 89% of IAs; 66% occur before 8 weeks; 14.5% occur at 9-10 weeks; 8.3% occur at 11-12 weeks. (data taken from 2013 https://www.guttmacher.org/fact-sheet/induced-abortion-united-states)