Fertility regulation in nursing women. VI. Contraceptive effectiveness of a subdermal progesterone implant

CONTRACE FE

ILl

R

S. D f a z ,

U

TI

IN N U R S l Subde

O. P e r a l t a ,

W N. VI. Contracept al P r o g e s t e r o n e plant

G. J u e z , P. M i r a

e Effect

C. H e r r e r o s , M.E. C a s a d o , a a~ H.B. Cro t to

A.M.

ION eness

Sal

of a

tlerra,

NSU ORIO P IFIC ION F ILIAR C e n t r o N a t i o n a l de la F ilia J.V. L a s t a r r i a 29 - D e p t o . I01 Santiago, I

ABST Six

progesterone

contraceptive w

an-

in

a

contemporary

after

fertility u

implants delivery.

vari

or i

problem

le r a t e

ant

of

Copper

an-

nths

The

ared

BER 1984 VOI.,. 3 0 NO. 4

of

after

in

the

trea=ed

rds.

There

the

occurrence

to the m a

fact

in 1614

pregnancies iactati

were en.

llfe

pellet i

The

at 30, 60 or 2 4 0 s 5 ous

n t h s and effects

the r a t e of c h i l d gr of

as

that o b s e ~ e d

re no d e l e t e and

tested

s diagnosed

either

effective

were

ilar

Nineteen

n lactation

related

S u b m i t t e d for p u b l i c a t i o n S e p t e A c c e p t e d for p u b l i c a t i o n S e p t e

ed

s s

en a d m i n i s t e r e d

duration

s

pregnancy

users.

obse

h e a l t h or u

One

subdermally

rate w h i c h

T

re e f f e c t i v e

encountered ich ap

men.

a failure

s quickly restored

n maternal

The main

group

in the 677 w

progesterone

implanted

d for l a c t a t i n g

n t h s of o b s e r v a t i o n ,

diagnosed

days

t

pellets

T

expulsion

th. at

procedure.

er 12, 1984 er 17, 1984

311

a

CONTRACEPTION

INT

DU

ION The

riable

inhibition

a

fertility

ng i n d i v i d u a l s

delivery. duri

of

This

fact

lactation

and

dete

thout

tends

ines

associated to

with breastfeedl

decrease

as

time

elapses

th m i l k

production

following

that can be used

the need for c o n t r a c e p t i v e s

interfering

is h i g h l y

or child

health

(I,

2, 3)In of

using

previous the

breastfeedl six of

o the

the

D

to 3, no

a!

blti

ad

ogesterone of such a

ntages

contraceptive

is paper g i v e s

of

ntage8

a

tential ad

obtained with a s

tied°

eness

as

the

de

an

during

al

plant

updated

ministered

of

account

by this m e a n s

thod.

THODS

teers

e

enrolled

o met the

en

weight

results

re re

effect

discussed

progesterone,

ellmlna

the o b s e r v e d

Vol

postpartum

(4, 5)

ne,

sterone pellets

p~ation:

as

hot

contraceptive

E

c

lications

natural a

and d i s c u s s e s

birth

p

in the study Ii

requlr

a n c y and v a g i n a l

adequate

, free fr

to

the

drug

t

te

fr

ents:

18 to 35,

delivery

gestatlonal

ra

re selected

of

age.

and w i l l i n g

ages

a healthy They

to

a

had

healthy parity

1

with

a

infant

to

be

regularly

rse their i n f a n t s

as

long

s s!ble. Selectlon

tec

was

done

ique of b r e a s t f e e d l

the

time

physical and

of e

initiati inatlon

a normal

on de

of

nutritional

Progesterone

progesterone

pellets.

-

312

Progesterone

re gi re

was

pellets:

ere i n s t r u c t i o n s

postpart

re required

administered

by

control

injection.

evolution,

oglobin values higher

g r o w t h rate b e f o r e

subde

groups

on the

requirements

ditional

al

All cases

Contemporary

tlent

rd n.

no

ild, h

te i n f a n t

th an IUD or a placebo s at

nd

state.

Treatments:

d or an IUD

maternity

ther and

th an adeq

treated

the

treatment

breastfeedl

met

at

than

to be in

at

no

al

I0 g % c

sire

admission.

al were

The a l l o c a t i o n

insertion fo

ed

to

an

by

of s women

injectable

olce.

Pellets

were

made

OC

by c

esslng

R 19

I00

of the

V O L 3 0 NO. 4

CONTRACE steroid into a cylinder Three te

different

niques.

and p

III

t

received

6

region t

ough

ha

-

done

the

inserted at d pr

The

ter, o f f e r e d the

postpartum

as

a

test

fertility

month

placebo

disconti supple

at

two-month re

perfo for

boys

record per

ante (7)

all

as

i

t

III.

de

II was

subject

ally in the gluteal

wo

at

used

Each

Insertion

Pellets

re

n

of

petted

o

re

approximately

a

s

this study

Protecci6n

of

the

an

to

treated day

240

lactation with

and

therefore

breastfeeding.

fe~i

at

to

Women the

6th

s introduced. This

alone or

group

rtial

to dete

ine the occurrence of

th, s ~ e

effects a

was rsl

both

At

ther

e a c h visit,

a

ild

re c a r e f u l l y standa

. ys

Special

and

the

re

I

the m a t e r exa

er

of

pattern. month

I a

ned.

ted usl

calendars

egnancy,

bleedl

y intervals up to the sixth postpart

tti

using

ovlded poor p r o t e c t i o n (6).

ant gr

h

s

of distilled

contraceptives

rsl

It

groups

of 3

postpartum.

that full

illa).

contemporary

e n t a r y bottle 30

Copper T 2 0 0

s t

de la F

injection

sustain

day

=hereafter.

ant gr

a

at

ds

nt

=he reference

bleedi

de

in

associated

s designed

als

used

if suppl

ante, i

recorded

a

different

axis in batches

progesterone

batch

pellets

diameter.

ed usl

anesthesia.

non-hormonal

ident

rrler

inte

of

to

re offered earlier

perfo

in

delivery.

to m a t c h

inhibition

re scheduled at

histories

IUD

treatment

Follow-up

breastfeeding

The

cordingly,

consisted

administered

th

:

set

Chilena

en it bee

nted

Visits

or

was

ed

Follow-

The

placebo

enrolled in this group

The

I.

local

nths.

30 or 60 p o s t p a r t u m llets.

3.2 m m

re still nursing their babies.

Asociaci6n

esterone

by

manufact

re inserted s under

60 a f t e r

a second

device:

- Placebo:

support

in b a t c h

trocar

30 or

they

Intrauterine by

it

life of 5 or 6 offered

length

III)were

llets t h a t

at d a y

provided

(supplied

to

a No. 9 g a u g e

60 w e r e

rtum

and

es I and II and p r e c o m p r e s s e d

an effecti

post

II

rely 11.8 m m

s applied along the L o n g i t u d i n a l

esterone

was

at day

(I,

pression

perpendicular

dered in

pellets

batches

C

and

of approxi

ION

and

infant

Breastfeedi

the B o s t o n curve re

distributed

breastfeedi

to

episodes

day. Pregnancies

ER 19

were

diagnosed

VOL. 3 0 NO. 4

by

clinical

examination

and

urinary

313

CONTRACE

unologleal delayed

ION

tests

for 20 days

month and before 240 a f t e r

during

a

or mote,

en

.....l. e,v e l s :

subsample

of

the f i r s t

levels

Pregnancy

the i n s e r t i o n

e ........b l o o d

a

.

tests ;were p e r f o r m e d

enorrhelc w

of a second

en reached

when m e n s e s the 6th

set of p r o g e s t e r o n e

were

stpart

pellets

at

day

dellvery.

P rogestero

fr

for H

segment

re d e t e ~ i n e d

reagents

Reagents

the

of u s e

by

RIA

s

and

as

the

of

ples

re

dr

of the 3 d i f f e r e n t

by R

provided

for

Blood

users

from

n

at

control

Programme

for

in

the

!5-day

inte~als

of p r o g e s t e r o n e

pellets

subjects.

Progesterone

(8) usi

the p r o c e d u r e s

iously described

Hormones

10-or

batches

Provision

Reproductive

of

Matched

Physiology

of

Assay

the W o r l d

Health O r g a n i z a t i o n .

Dat~a anal s l s : first

day

of

the

when possible The

Pearl

inte

The m o n t h last

Index

was

used

treat

L_actatlon w a s

:baby.

bleeding

by r e f e r e n c e

Is d u r i n g

exclusive

of c o n c e p t i o n

the

classified

6th month,

source

milk. was

Supplement indicated

production The

by and

the

~In

s confl

o

age

14 days

to the

ed or a d j u s t e d of

the

b i l i t y of p r e g n a n c y

neonate. at v a r i o u s

to the 6th m o n t h

food

full of

the

was

nursing cases

effect

of age

source

if

the

remaining of

In se

based

her

was

in

full

the upon

or

for the

routinely

breast

treatment

ral cases,

upon

as full nursi

of n u t r i e n t s

prescribed

by the p e d i a t r i c i a n w h e n

m i l k supply. mother

s the only

the

and only

nursing

lactation.

the rate of infant g r o w t h the

subjective

supplement

was

evaluation

self-

of m i l k

child s a t i s f a c t i o n .

of

gro

mother

of and

severe

interc!irrent disease,

child,

dete~ined

discontinuation

cluslon

of the case fr

h follo-w~,ng the la3t visit

order

rage a b s o l u t e

314

as

to a s s e s s

occurrence

los t - t o - f o l l o ~ u p and infant

up

proportion

prescribed

inadequate

prescribed

separation

The

used

was

te the

non-dalry

s still c l a s s i f i e d

condition

It

ted g e s t a t i o n a l

if the breast

lactation of

by adding

observed.

to the esti to est

ated

nt.

breastfeedl

After

run

s est

to

assess

the

ight at e a c h

effect

of

prior

prolo of

ed or repeated treatment

analysis

or

o~ l a c t a t i o n

to the event.

treatment

nth of llfe and the

upon in~ant growth, Ight

rage

R 19

V

the

increase

30

4

CONTRACE

at m o n t h l y and daily exclusive month

through

occurrence

the p r o p o r t i o n

spottl

of

included.

for e a c h group.

Calculations

statistical

respectively.

uncomfortable

of

per 3 0 - d a y

Contingency the

re c a l c u l a t e d

were

Only

cases

in

re d o n e up to the 8 t h

of age. The

plus

intervals

breastfeedl

ION

n

after

table a n a l y s i s

0nly p values

prolo

o experienced

inte~al

significance

or

re t h a n

was a n a l y z e d

6 days

of

bleeding

ent.

trea

and s t u d e n t ' s

of d i f f e r e n c e s

<0.05

ed bleedl

"t" t e s t

were used

to

assess

in d i s t r i b u t i o n and m e a n values,

re c o n s i d e r e d

significant.

~SULTS The Table

I.

number

Ninety-two

progesterone

pellets

The plasma of

of

pellets

subjects

out

of

batches

progesterone

in

to

of

tolerance

subjects

varied

Table

II

This

the

thereafter

the

the

is s h ~ n

in

relnsertion

of

3 different

their ~ x l m u m

remaining

group.

according table

nursing

elevated

Levels

batches

within

ten days

at least

obtained

in

one

the

pregnancy

was

I in

inhibition

obtained w~th

treatment

groups

showed

for

w i t h the 3

t

e elapsed

of

pregnancy

breastfeeding the

months.

was

s diagnosed

status

from

batch

II

insertion

5

in

insertion.

This

figure

significantly

and

the

months

at

day

The

overall table

postpart incidence

of

each

month

nths of 30,

with

time

after

rtlally nursl

is c

lower

treated

the 8th p o s t p a r t u m

given

the C o p p e r T in the s

O-CToBER 1 9 8 4 VOL. 3 0 NO. 4

Expulsion

between

in w o m e n

first

this reason,

after

poor.

to five months.

treatment

month

a

was

re obse~.,ed in the first 5

when

1614

~e

only

For

pregnancy

4th

days

pellets

I, in 31.7% of s u b j e c t s

Ill.

to t h e

insertion.

women

Only

batch

includes

No p r e g n a n c i e s

postpartum.

progesterone

occurrence

not

occurred

~th

They r e a c h e d

from b a t c h

plant

included.

to

from

progesterone

it

accepted

group

at day 240 ~ s t p a r t u m .

control

from s e v e r a l

shows

pellets

treatment.

full

i.

the

in 2.4% of subjects 9.9%

and e x p u l s i o n

in

(82.1%)

treatment

of s l m i l a r m a g n i t u d e . local

progesterone

in each

levels a c h i e v e d

gradually

comparison

were The

and

women

are show~n in F i g u r e

in

occurred

I12

that was offered

of i n s e r t i o n and d e c l i n e d 5 months

enrolled

is

urea

ent

or

240

w~en

and

60

incidence

of

to the f e r t i l i t y intervals. of

pregnancy

Both as

315

CONTRACE

ION

I

Distribution

of S u b j e c t s A c c o r d l

and Day of

I n i t i a t i o n of Trea Postpart D

ent

to Trea

nt

inistration

No. of S

Jeers

P r o g e s t e r o n e Pellets D

30 :

D a y 60:

Day 240:

Batch !

84

Earth II

41

Batch III

152

tch Ill

92

Copper T

D

30

125

60

121

30

130

Placebo

D

316

R 19

VOL. 3 0 NO. 4

CONTRACE

ION

ng/ml Q Batch I 6

o

B a t c h II

0 Batch Ill

4

m

.

on,

o

a

~Im

a

,

•

,

,

*

o

÷

¢,

*

•

O .........- ~ - -

~

°~'T=--~ ....: - i

.............. ~.

........................,....... . . . .

30

0

, ............................... ......=..

i

.... ~ .... -, .....

60 TREATMENT

Fig.

i"

Plasma

progesterone

th p r o g e s t e r o n e

levels

pellets

19

VOL

30 NO. 4

........ l .............

...................... - - =

. .......

120

-,

. . . . . . ..... .............

150

DAYS

(X +

from

Batch III (o) and in control

BER

- ....., .......

90

S.E.)

Batch

cases

in lactati

I ([~),

Batch

w

en treated

II

(~)

and

(e).

317

CONTRACE

ION

BLE II

Contraceptive Placebo

Treatment

Progesterone Pellets

Copper T

Placebo a

Effectiveness

cording

to the Breastfe

Breastfeeding Status

a b c d

318

i

P e l l e t s versus C o p p e r T and

Status

and the O b s e r e a t l o n P e r i o d

No. P r e g n a n c i e s / No. man-months Ohse~,,a tlon Period* (Po 8 t pa r t Hon th s ) 2 - 68

3 - 7h

9

0/339 0/17 0/10 0/366

0/594 I1199 0/37 1/830

0/144 0/205 0/69 0,/418

~/16!4

clusive Supple nted Weaned 1

1/471 0/43 1/514

0/420 0/164 0/'39 0/623

1/252 0/268 0/72 1/592

2/1,729

Exclus e Sup pleme n ted Wean

91502 4 / 49 i3/551

clus Supple Wean 1

l *

of P r o g e s t e r o n e

e nted

-

13c

TOT

1/49 5/77 -

6/126

t9/677

13, the first five nths postpartum ~ I I o ng i n s e r t i o n were c o n s i d e r e d el e this is the eat ated effective llfe of p r o g e s t e r o n e plants (See Tab le II I). Treatment Inltlat at day 30 ~ s t p a r t . Trea ent i n i t i a t e d at day 60 postpart . Trea nt initiated at day 240 post rt in p r o g e s t e r o n e pellets gr p and at day 30 or 60 in the oEher o groups. S e m e n used s £clde8 ~fter the s i x t h p o s t p a r t n~h.

BER 19

VOL. 3 0 NO. 4

NTRACE

compared 677

to the place

a

Table

III

progesterone

months to

of

pellets

nth8

W

use.

The status at

a~

day

th of

of to

according No

obse~ed

240

h

regardless

during obse

the

six

of the

first

tlon

dla~nosed

in T a b l e

IV.

breastfeedi

c a s e s ~t

age.

through

five

s extended

i~

239

72

and

e 6th

Treatment

evolutions

initiated

at

day

n

of

8

Values

fo~

groups

s

60

c

ilar

to

showed

a

pared

to the

side

first

~ w

e

al.

of t r e a t

nt.

postpartum,

groups

month

of

6 or

bleedi

use

s of b

6Z

(third

month).

~rlod,

the ran

within

at

each

Table V s

the

birth

to the

normal

range

pattern

the p r o p o r t i o n

edln~ p

who

reported

s spotting ps after

more

nth of treatment) r T use

sh

to

comparable

in all gr

o p o r t l o n of Cop d fr

bleedlnH

ed

=hat

of full per

30-

the first

of the secon~ set of i m p l a n t s

ranged

sa

Ight

ass.

ants ~ fr

pellets

re d

s infrequent

bleedln E per interval

s of bleeding

of

ble VI sho

women

In t

i

The

T.

tar the i n s e r t i o n

fr

were

detected.

of

re than 6 d

the

ely b r e a s t f e d

re

a Copper

erienced

cessna

body

Ight inc

comparlson.

effects

the

i l a r In treated and

s s

absolute

daily

all

the s t a n d a r d used f

~nf~ts

the averase

y a

proportion

DIS

of

~ng to their breastfeedi

co

B o t h serie~

e mont

after ~ n s e r t l o n

day inte

sho

rt

eared

crease

during

nursing

n

elusively breastfed

the aver

m~Jor

disruption

1

of

is

ps.

en analyzed

ight

month

gr

ths,

w~re

the

at day 30.

groups

the a v e r a g e

of su

st

in

ely.

nth

or 60

le

en t

6 pregnancle8

diagnosed

is.

effectiveness

effective

decreased

respect

~ere

rtum inte

treatment

hlghly

distribution

ntrol

proportion

nth of age and

n

30

orary

started

control

3 and

e,

of expos

T h e gr

6th

ere

cumulates

thelr coat

series

was

st

contraceptlve

different

for

Treatment

7

19 p r e g n a n c i e s le

overall

the 6th postpart

~nltlated

higher

the

i par

The e f f e c t i v e n e s s

6 and

n-months

p in

ed in c

shows

of i n s e r t i o n .

ti

gr

obse

nthe

ION

at

day

than 6 days of to

16Z

(flfth

o experienced

21~ to 31%.

SSION The

progesterone

results by

of

this

st

y s

ans of an ~mplant

BER 1984 VOL. 30 NO. 4

i

w that the cont~ ibits f e r t i l i t y

ous

mln~stration

in l a c t a t l n g

women

of and

.t19

CONTRACE

ION

TA D u r a t i o n of t h e

Contracept

Months of Treatment

1 to 5

E III

e E f f e c t i v e n e s s of S!x P r o g e s t e r o n e Pellets

Pregnancies/ Wo nths

Pearl Index

!/1614

6

3/239

7

6/72

0.74 15.1 I00.0

R 19

V O L 3 0 NO. 4

CONTRACE

TABLE

C

A

en Accordlr~

to their

Condition at the 6th P o s t p a r t u m Month

Insertion (Postpartum day)

NT

IV

ulatlve D i s t r i b u t i o n of

Breastfeedi~

ION

Excluslve Breastfeeding

z

Use

of S u p p l e m e n t a ~ Feedi dical ternal Prescriptlon Decislon Z z

Progesterone Pellets

Cop~r

30

T

Placebo

N ffi N *

~ses

68

21

11

60*

127

53

39

7

30

106

60

29

11

60

105

50

36

14

30

105

71

26

3

er of cases observed at day 180. treated w~th pellets

bias introduced

OC

73

BER 19

from Batch II ~ r e

by the high nu

VOL. 3 0 NO. 4

excluded because of the

er of expulsions.

321

CONTRACEPTION

TABLE V

erage W e i g h t

Increase

of Exclus~.,ely B r e a s t f e d

Infants

from Birth to the 6th M o n t h of Age

I n i t i a t i o n of T r e a t m e n t (Post rt Days)

Progesterone

N

~~ght

Increase X + S.D.

(g)

Pellets

Day 30

46

4515 + 621

Day 60

60

4730 + 670

Day 30

64

4801 + 817

Day 60

49

4798 + 546

Day 30

68

4663 + 529

Copper T

Placebo

322

B E R 19

VOL. 3 0 NO. 4

CONTRACE

ION

BLE Vl

Percentage

of Full Nursi of Bleedlng

te al (Postpart days )

31

Women who Experienced

or Spotti

Progesterone 30*

More

than 6 D a y s

per 30-Day I n t e ~ a l

Pellets 60*

Copper T 30* 60*

Placebo 30*

-

60

46

-

52

-

61 -

90

12

18

10

30

4

120

8

5

14

16

5

91-

22

121

-

150

6

5

12

15

8

151

-

180

9

4

17

15

7

*

Postpart

B E R 19

day of insertion.

VOL. 3 0 NO. 4

323

CONTRACE

that

it

can

during

ION

be

the

used

period

satisfactory

and

pregnancies

of

of

The

the

duration

preg

observed

ncles

n

o

ness

the

elevated

iactati

Treatment

with

proportion

of

also

at t

to io

-te

subjects

or

partially

related

The

high

s the conc

is

highly

incidence

slon that

of

the 1

exclusively

by

to 5 be

levels

nths.

inferred

After from

.

of

1

an

this period,

the

number

of

is led us to

of the first rese incidence

reassuring during

and

of

olr to

egnancies

of

the

contraceptive

lactation

and

shows

that

its

ed no ad

infants

n.

up or

risk

for

to

the

6th

a Copper

did

the

s

T

than

less,

and

effects

on

e breastfeedlng

more

eft

period

rse side

clus

lactation the gr

postpartum resulted

6 days

this not

a

of

in

month. a higher

bleeding

s a transient represent

jeers,

th

a

as

obl

reason

deleter

,

for

s effects

re d e t e c t e d . of

expulsion to

women

indicates

problem

efforts

ogestero

is

experienced

a health

plants main

of

3

steroid

determined

haustlon

t tl

pellets

treat

incidence

justify n

who

percentage

progesterone

ind

postlnsertlon

the

The

of

the

observed

lactation.

breastfed

t health

The

rate

nth after insertion,

the

plants

progesterone

discontinuation u p o n Inf

of

progesterone

can

o r t i o n of cases in

to t to

as

segment

of p r o g e s t e r o n e

exclusively

pared

pregnancy

IUD.

not

s limited

after

e u s e of p r o g e s t e r o n e

limited

T

plasma

restored

second

as j u d g e d by the

c

was

at the 6th and 7th

re still in

of

levels

g r o u p all

groups

set of I m p l a n t s

efficacy applies

rate

e

of a C o p p e r

efficacy

quickly

second

effectl

of

contraceptive

observed

plasma

in the p l a c e b o

treated

was

wo

elevated

thin the r a n

fertility

a

purposes,

.

breastfeedi

offer

contracepti

observed

fertility

acceptable

for

who

were

that this is a

encountered of

the

el

an

this

progesterone

o

to

pellets

st

a

second

alternatl

experience

technique. d

use

Ii a c c e p t e d

during

the m a n u f a c t u r i n g

to d

willing

Ich The

r the

was

set . the

appears

of

high

to

be

results

reported

long-term

delivery

.

OC

R 19

V O L 3 0 NO. 4

CONTRACE

A

EDGE

NTS

The

authors

Jaraquemada provided

and

are

the

grateful

Central

for this study,

progesterone Reagents

pellets,

for

the

for

to

the

Health

authorities

Area

of

of

Santiago

the Hospital Paula

for

the

facilities

to the Instituto Bioqufmlco Beta for the provision of

to the

RIA

of

International Develo Committee

ION

0 Progra

Hormones

for the Provision

in R e p r o d u c t i v e

nt Research Centre of Canada and

Contraception

Research

of T h e

of

tched

Physiology, to

the

Population

and

Assay to

the

International

Council

for their

The chance of conception during lactation.

J Biosoc

support. FE

I

e

0

NCES

Van

Ginneken,

J.K.

Sci,

Supp 4-41-54

Lau

ran, V.H.

Contraceptive

postpartum family O

McCann,

M.F.,

lactancia

(1977).

planning.

Liskin,

choices

Stud Faro Plann

L.S.,

materna,

la

Croxatto,

fecundidad

H.B. , D~az,

Salvatlerra,

A.M.

II. Comparative Copper T. O

Croxatto, M.E.,

and

perfo

H.B.,

D~az,

rkshop on Long-Actlng D ~ a z , S. , P e r a l t a , Dur~n,

E.

and

randa P.

in

rsi

Juez,

Croxatto, H.B.

e probability of conception setti 0

.

Editor.

Philadelphia P.A., 0

Croxatto, A.

Plas

G.,

H.B.,

progesterone

familiar.

full

G. , C a s a d o ,

implants

M.E.,

versus

placebo

and

(1982).

O., Suez, G., Herreros, Subdermal

at the s.

Salvatierra,

nursing

C., Casado,

progesterone

Delivery Syst

P

A.M.,

implants

International FR~

May 1983.

Casado,

M.E.,

in nursing women.

~omen

living

in a n

I.

urban

(1982).

T e x t b o o k of Pediatrics,

1964. DKaz,

La

regulation in nursing women.

Fertility regulation in

J Biosoc Scl 14 -329-341

Nelson, W.E.,

W. and Fox, G.

planlfleaci6n

women. Presented

Contraceptive O.,

for

(1981).

Rinehart,

O. , J u e z ,

Fertility

S.... , Peralta,

for fertility regulation

O

E.

ecol 144:201-208

A.M. and

la

suggestions

1982.

nee of progesterone

J Obstet G

Salvatlerra,

y

S. , P e r a l t a ,

Dur~n

12:156-163

Piotrow, P.T.,

Population Reports J 24, October I

for lactating women"

8

ed.

W.B.

Saunders Co.,

p. 42. S.,

Peralta,

levels

folio

terone pellets in lactating women,

O C T O B E R 1984 V O L . 3 0 NO. 4

O., Sal ng s

de

tlerra, a!

ta Endocrinol

A.M. and Brandeis,

plantation of progesI00"630-633

(1982).

325