SETTING AND STUDY DESIGN

4.2.1 STUDY I

Municipalities in Finland have been obligated to offer contraceptive services for all citizens free of charge since 1972.¹⁷⁴ However, it is not specified how and where the services should be arranged, and the services might have changed over time. Therefore, the content of the services differs between municipalities as well as within each municipality between years. This allowed us to examine the association of teenage contraceptive services with teenage pregnancy rates in Finland at the municipality level. Since teenage pregnancy is associated with socioeconomic and educational disadvantages,^12,13 we took into account the socioeconomic status of each municipality. Specifically, in this longitudinal study, we analysed the combined association of regional, socioeconomic and adolescent contraceptive service variables with the annual teenage childbirth and induced abortion rates in the 100 largest municipalities in Finland. The

follow-up time was 19 years, from 2000 to 2018, encompassing 1 900 measurement points across the follow-up period.

4.2.1.1 Explanatory variables

We used the regional, socioeconomic and contraceptive service variables as explanatory variables for the annual teenage childbirth and induced abortion rates. Descriptions and variable types of the explanatory variables are presented in Table 8.

We aggregated the municipalities into larger areas based on the five major regions in Finland: Helsinki-Uusimaa, Southern Finland, Western Finland, Åland and Northern and Eastern Finland. Åland has only one municipality in our study setting and was thus combined with Southern Finland.

We obtained data on socioeconomic variables from the Finnish health registers, as described above in Table 7. However, to attain information about the contraceptive service variables, we conducted a questionnaire of the contraceptive services in municipalities concerning the centralisation of adolescent contraceptive services and the availability of free-of-charge contraception as well as when the services had become available. We got responses from all the 100 municipalities either by email or by phone. The states of adolescent clinics and free-of-charge contraception varied between the municipalities, but there were no breaks in the services during the follow-up.

Table 8 Descriptions and variable types of the explanatory variables.

Variable Description of the variable Variable type Regional Municipalities aggregated into larger areas

based on major regions in Finland:

Helsinki-Uusimaa

Southern Finland (incl. Åland) Western Finland

Northern and Eastern Finland

Nominal: values 1 to 4

Socioeconomic Social assistance recipients

Percentage of adults receiving social assistance in each municipality

Continuous:

percentages on the unit scale

Citizens with high education level

Percentage of citizens with a high education level: a university, a polytechnic degree, or studies of more than three years in a vocational institution

Continuous:

percentages on the unit scale

Available in all pharmacies in Finland for over 15-year-olds since 2002

Binary: values 0 or 1

Non-prescription EC for all ages

Available in all pharmacies in Finland without age restrictions since 2015

Binary: values 0 or 1 services within an adolescent clinic

Binary: values 0 or 1

Free-of-charge contraception until the age of 20 or 25

Municipalities offering all contraceptive methods free of charge until the age of 20 or 25

Binary: values 0 or 1

4.2.2 STUDIES II AND III

In studies II and III we explored the risk of psychiatric morbidity (study II) and premature mortality (study III) following teenage childbirth or induced abortion compared to women without a teenage pregnancy. In study II the psychiatric diagnoses and in study III the causes of death served as outcomes.

The psychiatric diagnoses and causes of death were coded according to the International Classification of Diseases, Ninth Revision (ICD-9) from 1987 to 1995 and the Tenth Revision (ICD-10) from 1996 until the end of the follow-up.

Initially, the cohort in both studies included all pregnancies among nulligravid girls under 20 years of age in Finland from 1987 to 1989 ending either in childbirth or induced abortion. Every cohort member had three age-matched reference members from the same municipality. We subdivided the cohort and reference groups into subgroups according to age at the beginning of the pregnancy: < 18 years old or 18–19 years old. The follow-up began at the time of childbirth or induced abortion in the cohort group and the same day (referred to as the index day) for the reference group. In study II the follow-up lasted until the end of 2015, and in study III until death, permanent emigration or 6 June, 2013.

In both studies, cohort members without age-matched reference members from the same municipality were excluded. The other exclusion criteria consisted of an incorrect identification number, non-disclosure of personal information, unknown municipality at the end of the pregnancy/index day and death before the end of the pregnancy/index day. Furthermore, in study II, the cohort or reference members who had emigrated after the end of the pregnancy/index day or who had a psychiatric diagnosis made before the end of the pregnancy/index day, were excluded. We excluded those with emigration in study II since possible psychiatric disorders diagnosed abroad are not available in the registers used in our study. After all exclusions, the total number of participants reached 52,755 in study II and 54,703 in study III. A flowchart of the study groups are presented in Figure 7.

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gure 7. Flowchart of the study groups in studies II and III.

All nulligravid teenage pregnancies and their reference members in Finland, 1987–1989 n = 52 755 (study II) n = 54 703 (study III) Teenage pregnancy n = 13 326 (II) n = 13 691 (III)

No teenage pregnancy n = 39 429 (II) n = 41 012 (III) Teenage childbirth n = 6 806 (II) n = 7 039 (III)

Teenage induced abortion n = 6 520 (II) n = 6 652 (III) < 18 years old n = 3 341 (II) n = 3 361 (III)

< 18 years old n = 1 794 (II) n = 1 816 (III)

< 18 years old n = 15 013 (II) n = 15 608 (III)

18–19 years old n = 5 012 (II) n = 5 223 (III) 18–19 years old n = 3 179 (II) n = 3 291 (III) 18–19 years old n = 24 416 (II) n = 25 404 (III)

4.2.2.1 Background variables

In the final analyses, we considered the sociodemographic factors of the women including type of residence (urban/semi-urban/rural) at the end of the pregnancy or the index day, and highest achieved educational level during the follow-up.^194,195 The educational level was classified by length of studies as high ( • 15 years), intermediate (11–14 years) or low (” 9 years of education).¹⁹⁵ Description of the educational levels are presented in Table 9.

In addition to the sociodemographic factors, we took into account the psychiatric morbidity of the parents and the number of teenage pregnancies as confounding factors in study II.

Table 9 Educational levels in Finland.¹⁹⁵

Educational level Duration (years) Classification in the present research

Primary education (compulsory,

begins at the age of 7 years)

6 Low

Lower secondary education (compulsory)

3 Low

Upper secondary education 3 Intermediate

Post-secondary non-tertiary education

1–2 Intermediate

Lowest level tertiary education 2–3 Intermediate/High Bachelor’s or equivalent level 3–4 High

Master’s or equivalent level 5–6 High Doctoral or equivalent level 2–4 High