Introduction

The teen pregnancy rate is defined as the rate of pregnancies (including live births, stillbirths, abortions, ectopic pregnancies and miscarriages) of women under the age of 20. In practice, the definition is limited to Manitoba residents and Manitoba hospitals. Research involving teenage pregnancy typically looks at women aged 15 to 19, but may consider a broader age range. For example, in Brownell et al. (2008) , teen pregnancy rates were also calculated for 12- to 19-year-old females, however the rate of teen pregnancy for females under 15 was very low; the patterns were similar to the 15- to 19-year-old female rates and so only the latter were reported.

Teenage Pregnancy was originally defined in the Assessing the Health of Children in Manitoba deliverable (Brownell et al., 2001). In the What Works? deliverable (Martens et al., 2008), most of the conceptual ideas surrounding teenage pregnancy remained the same, but the set of diagnoses and procedure codes used to define teenage pregnancy were modified slightly to focus on the mother's hospitalization, rather than the newborn.

Since 2008, MCHP published deliverables provide definitions for teenage pregnancy using ICD-10-CA diagnoses codes and Canadian Classification of Health Interventions (CCI) procedure codes.

Teenage Pregnancy Algorithms in Manitoba Data

The following definitions were used to define teenage pregnancy in MCHP research over time.

1. Brownell et al. (2001)

In the Assessing the Health of Children in Manitoba: A Population-Based Study deliverable by Brownell et al. (2001), the following ICD-9-CM diagnoses and procedure codes were used to define teenage pregnancy outcomes. Teenagers were defined as being 15-19 years old.

ICD-9-CM Diagnoses Codes


• 632 - Missed abortion
  
• 634 - Spontaneous abortion
  
• 635 - Legally induced abortion
  
• 636 - Illegally induced abortion
  
• 637 - Unspecified abortion
  
• 656.4 - Intrauterine death
  
• 761.4 - Ectopic pregnancy
  
• 779.6 - Termination of pregnancy
  
• V27 - Outcome of delivery (includes live birth and stillbirth)

ICD-9-CM Procedure Codes


• 69.01 - Dilation and curettage for termination of pregnancy
  
• 69.51 - Aspiration curettage of uterus for termination of pregnancy
  
• 74.91 - Hysterotomy to terminate pregnancy
  
• 75.0 - Intra-amniotic injection for abortion

2. Martens et al. (2008) and Martens et al. (2010)

In the What Works? A First Look at Evaluating Manitoba's Regional Health Programs and Policies at the Population Level deliverable by Martens et al. (2008) and the Health Inequities in Manitoba: Is the Socioeconomic Gap in Health Widening or Narrowing Over Time? deliverable by Martens et al. (2010) the following ICD-9-CM diagnoses and procedure codes were used to define various pregnancy outcomes:

ICD-9-CM Diagnoses Codes


• V27 - Outcome of delivery (includes live birth and stillbirth)
  
• 632 - Missed abortion
  
• 633 - Ectopic pregnancy
  
• 634 - Spontaneous abortion
  
• 635 - Legally induced abortion
  
• 636 - Illegally induced abortion
  
• 637 - Unspecified abortion
  
• 656.4 - Intrauterine death

ICD-9-CM Procedure Codes


• 66.62 - Salpingectomy with removal of tubal pregnancy
  
• 69.01 - Dilation and curettage for termination of pregnancy
  
• 69.51 - Aspiration curettage of uterus for termination of pregnancy
  
• 74.3 - Removal of extratubal ectopic pregnancy
  
• 74.91 - Hysterotomy to terminate pregnancy
  
• 75.0 - Intra-amniotic injection for abortion

NOTE: The following two diagnosis codes were reviewed and a decision was made not to use them in the What Works? definition because they relate specifically to a newborn hospital separation (abstract) record, not the mother's hospital separation (abstract) record. These are:


• 761.4 - ectopic pregnancy; and
  
• 779.6 - termination of pregnancy, fetal death.

3. Brownell et al. (2008)

In the Manitoba Child Health Atlas Update by Brownell et al. (2008), they investigated teenage pregnancy from the perspective of both the mother and the newborn. In addition, the definition for teenage pregnancy involved both ICD-9-CM and ICD-10-CA diagnoses codes, as well as procedure codes using ICD-9-CM and the Canadian Classification of Health Interventions (CCI).

The diagnoses and procedure codes used in this deliverable are located in separate files, accessible from the Links section below.

4. Martens et al. (2010), Chartier et al. (2012), Brownell et al. (2012) and Smith et al. (2013)

In Profile of Metis Health Status and Healthcare Utilization in Manitoba: A Population-Based Study by Martens et al. (2010), Health and Healthcare Utilization of Francophones in Manitoba by Chartier et al. (2012), How are Manitoba's Children Doing? by Brownell et al. (2012) and Social Housing in Manitoba by Smith et al. (2013), teenage pregnancy is defined as females with a hospitalization with one of the following diagnoses:


• live birth: ICD-9-CM code V27, ICD-10-CA code Z37
  
• missed abortion: ICD-9-CM code 632, ICD-10-CA code O02.1
  
• ectopic pregnancy: ICD-9-CM code 633, ICD-10-CA code O00
  
• abortion: ICD-9-CM codes 634-637 ICD-10-CA codes O03-O07; or
  
• intrauterine death: ICD-9-CM code 656.4, ICD-10-CA code O36.4

Or, a hospitalization with one of the following procedures:


• surgical termination of pregnancy: ICD-9-CM codes 69.01, 69.51, 74.91; CCI codes 5.CA.89, 5.CA.90
  
• surgical removal of extrauterine (ectopic) pregnancy: ICD-9-CM codes 66.62, 74.3; CCI code 5.CA.93
  
• pharmacological termination of pregnancy: ICD-9-CM code 75.0; CCI code 5.CA.88; or
  
• interventions during labour and delivery, CCI codes 5.MD.5, 5.MD.60

In Martens et al. (2010), Chartier et al. (2012) and Smith et al. (2013), this was restricted to females aged 15-19. In Brownell et al. (2012), this was restricted to females aged 13-19.

In Smith et al. (2013), the ICD-9-CM procedure codes were expanded to include all codes in the range of 74.x (caesarean section and removal of fetus).

5. Fransoo et al. (2019)

In The 2019 RHA Atlas Indicators deliverable by Fransoo et al. (2019), they included live births, still births, ectopic pregnancies, abortions and miscarriages for females aged 15-19 to identify teen pregnancy. This was defined by a hospitalization in Manitoba with ICD–10–CA codes Z37, O00, O02.1, O03, O04, O05, O07, O08, O36.4 or CCI codes 5.CA.xx, 5.MD.5, 5.MD.60.

They also noted that abortions performed in private clinics were not included in the count of teen pregnancies, because we do not have this data in the Repository.

For more information from this research, see section 10.15 Teen Pregnancy Rate in the deliverable.

Limitations / Cautions

• Diagnoses and procedure codes should be reviewed at the beginning of every research project to check for revisions or additional information on the current use of the codes, based on the nature and focus of the research. For research focusing on pregnancy outcomes, two different codes for ectopic pregnancy are available. One is used to code the mother's hospital experience, and the second is used to code the newborn's hospital experience. Using both could lead to double-counting the event.
  
  
• The teenage pregnancy definition is based on an endpoint of pregnancy (live birth or other outcome) rather than on a diagnosis made during the pregnancy (e.g. V22, Supervision of normal pregnancy, or V23, Supervision of high-risk pregnancy). Pregnancies among people having no prenatal visits may not be captured by a definition assuming some level of prenatal care.
  
  
• Errors due to miscoding - In rare cases, miscoding of diagnosis V632 as 632 may lead to elderly women being included in the sample.
  
  Example : Two cases from Fiscal years 94-98 are identified with diagnosis 632, but have ages well over 80 years. These are likely miscodes of V632 (Person awaiting admission to adequate facility available elsewhere). This is made even more likely by the presence of V632 on one of the cases and V631 (Medical services in home not available), on the other.
  
  Other diagnoses on the claims are compatible with advanced age, so the birth dates are likely correct.
  
  The restriction to age 15-19 in the Child Health deliverable dropped these cases, but any analysis of an unrestricted age group would include them.
  
  • Be aware that miscoding of this kind may occur, and check any cases with unusually high ages.
    
  • Rule out error in birth date by checking against the Registry. If that is not the problem, one of the diagnoses may be miscoded.
    
  • With advances in reproductive technology, what is considered an 'unusually high age' is constantly changing, so, if in doubt, consult an expert in the field.
  
  
• Notes from Martens et al. (2010)
  • abortions performed in private clinics are not included in the count of teenage pregnancies.
    
  • The rate of pregnancies in teenage girls aged 10-14 was not analyzed due to the small number of events.
    
  • There is a possibility that there is missing data for this indicator because of an inability to pick up nurse practitioner, nursing station, and salaried physician work.