Monday, November 28, 2011

Is Home Birth Safe?

This is another entry in my series on Pregnancy and Birth Outcomes based on the Washington state birth certificate data.

The Business of Being Born Again has just been released.  Which of course sparks the never ending discussion on whether home birth is safe or not.  I have not seen the new documentary, but the original Business of Being Born makes the premise that hospital birth is more dangerous than home birth because of the overuse of interventions, specifically induction, augmentation and an epidural.  The movie states that even women who want to avoid these interventions are pressured into them by the care providers in a hospital for a variety of reasons, including that it is more convenient for the staff, and they make more money.

I have been working on this analysis for a long time.  I kept waffling on whether it would be better to post analysis of each type of intervention, and then home birth, or vice verse.  I struggled getting the most fair, accurate, and mathematically correct analysis, and of course making all the data presentable and understandable.  I am also a bit scared because this is a topic that can get heated and I would prefer not to be the target of a barrage, but I think this information is important enough that I am willing to put myself out there.

Once again I'll start with the conclusion and work backward for the googlers who need answers at the top of the page ;)

CONCLUSION
In Washington state midwives are licensed, regulated, and are able to carry life saving medications that include anti-hemorrhagic, anti-seizure medication, intravenous fluids, epinephrine, oxygen and antibiotics for the treatment of group B strep infection.  Home birth is legal and is required to be covered by insurance (if the insurance covers maternity care).  Under these conditions from 2002 - 2007 for babies born between 37 - 42 weeks gestation home birth had overall better outcomes for both babies and mothers than low risk births that took place in a hospital.  Even when compared to births at a hospital that were not induced, augmented or made use of an epidural, births that took place at home had overall better outcomes for babies and mothers.   


RESULTS


Results highlighted in yellow are considered statistically significant, while those that are not highlighted are not considered so.  Click on the small thumbnail to see the table that includes the confidence intervals.

Home Birth With Attendant:  Births that happened at home or were planned on happening at home with the supervision of a care provider.  The care providers were mostly licensed midwives, but also included certified nurse midwives, osteopaths and doctors.  The births were between 37 - 42 weeks gestation.  I did not restrict the results to low risk, so the data includes VBAC's and other complications that the attendant apparently felt comfortable enough to attend the birth at home.

Low Risk Hospital: These are all the births that happened at a hospital and were planned to happen there. The births were between 37 and 42 weeks gestation.  Only low-risk patients were included in the data set so women that had  diabetes, hypertension, previous preterm births, other previous poor pregnancy outcomes, vaginal bleeding during this pregnancy prior to the onset of labor, pregnancy resulted from infertility treatment, had previous cesareans, Group B strep, were carrying multiple babies, had an incompetent cervix, had preterm labor, had a external cephalic version, received steroids (glucocorticoids) prior to labor, or the baby was breech or transverse were excluded from the data.

Click to enlarge


Click here to view all data including confidence intervals.



  • The rate of adverse outcomes for the baby were approximately 6.5 percentage points higher for hospital births than home births.  (6.4 percent vs 12.9 percent).  This reflects complications occurred almost twice as often.
  • There was a statistically significant better rate of outcomes in home birth for NICU admittance, assisted ventilation required for more than 6 hours, intolerance of labor and meconium staining amniotic fluid.  For all other outcomes there was not a statistically significant difference between the two. 
  • The rate of adverse outcomes for the mother were approximately 8 percentage points higher for hospital births than home births (2 percent vs 9.9 percent).  This reflects complications occurred more than 5 times as often.
  • There was a statistically significant better rate of outcomes for home birth among 3rd and 4th degree perineal lacerations and initial cesareans.  The differences between all other categories were not considered statistically significant.  
  • The rate of home births that transferred to a hospital was about 5.7 percent.  This includes mother's or baby's being transferred after the baby was born.  I initially published this with a lower number (3.6 percent), but that only counted transfers that occurred before the baby was born.  Thank you Annie for suggesting this number was too low.

Natural childbirth advocates claim that interventions cause many of the complications in hospital births.  I compared home birth to hospital birth where the labor was not induced, augmented, or made use of an epidural.  The data otherwise is the same as above.

Click to enlarge


Click here to view all data including confidence intervals

  • The rate of adverse outcomes for the baby were approximately 1.3 percentage points higher for hospital births than home births.  (6.4 percent vs 7.7 percent).  
  • More babies received assisted ventilation immediately after being born at home than at the hospital (1.4 percent vs 2.8 percent).  This reflects that this happened almost twice as often at home than at the hospital.  
  • More babies did not tolerate labor so that in-utero resuscitation measures, further fetal assessment or operative delivery at home than at the hospital.  (.29 vs 1.3).  This reflects that this happened about 5 times as often at the hospital than at home.
  • There was less staining of amniotic fluid with meconium among babies birthed at home than at a hospital. (1.7 percent vs 3.4 percent).
  • The rate of adverse outcomes for mother were approximately 1.7 percentage points higher for hospital births than home births. (5.5 percent vs 1.9 percent).  This reflects that complications occurred almost twice as often at the hospital than at home.
  • The rates were better for home birth for 3rd and 4th degree perineal tears.
  • The rate of initial cesarean was approximately 3 percentage points higher for intervention free hospital birth than home birth. (1.3 percent vs 4.3 percent).  This reflects that cesareans occurred almost three times more often among hospital births than home births.

Sometimes people will allow that home births are safer in the less serious outcomes, but when something bad happens your baby is more likely to die if you are at home.  Unfortunately the statistics regarding deaths are somewhat unreliable.

There are two fields used to describe mortality.  One is a link with infant death records.  This records that a baby died sometime in the first year, however the cause of death could be completely unrelated to its birth.  Another field that is used is whether the baby was alive when the birth certificate data was recorded.  There was a note about data quality saying that before 2005 there were records that said the baby was not alive, but there was no death certificate that matched the record.  It said this number was corrected after 2004, however there were many records after 2004 that said the baby was not alive, but it did not also have the field that linked the death certificates marked.  The majority of these records that had the discrepancy did not have any corresponding birth complications associated with them (ie resuscitation, NICU stay, etc) so I am assuming these records were probably marked incorrectly and thus this field isn't meaningful.

The second measurement of mortality are baby's who are not born alive otherwise known as still born.  These records are stored in a different database because the babies do not have a birth certificate.

In an effort to be unbiased I provided a few different rates for comparison.

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  • The differences in mortality rates between home birth and hospital birth were not significant.
  • Using the most accurate data in the defined parameters (full term birth, born at home, on purpose, with a trained attendant vs low risk hospital birth) the actual outcomes were more favorable for home birth.
  • I included rates for home births of unknown planning with unknown attendants for curiosities sake and allowed babies from 36 wks gestation as well.  Even these were either only slightly worse, or better than the hospital births rates.
  • The "Not Alive When Reported" rate was poorer for home birth, by quite a bit, but as I mentioned earlier, this field is extremely questionable in its accuracy.  

DISCUSSION

Is birth safe?
Yes, but not really.  The best rates above have around a 5 percent chance of something wrong happening.  That doesn't sound like a lot, but when you phrase it as a 1 in 20 chance.  It would mean that 5 out of your 100 female/mommy Facebook friends would have had some less-than-ideal birth experience (unfortunately I was one of those five)--not rare and unheard of.  Also those optimum rates were for low risk pregnancies.  There is a high percentage of pregnancies that aren't low risk, so overall the rates might be (really I have no clue) more like 10 percent (1 in 10) to 15 percent (1 in 6ish).  Thankfully, with modern medicine, the vast majority of the time the less-than-ideal outcome doesn't last more than a few weeks (perhaps which is why there doesn't seem to be much effort in trying to improve it?).


Is home birth safe?
Yes, in Washington state, it has been safer than hospital birth for low risk pregnancies.

Does this mean home birth is always safer?
Probably not.  It is illegal for midwives to deliver babies at home in many states, or it is illegal for them to carry medications or administer antibiotics.  If proper backup is not available it is likely the results would not be so favorable.  This analysis is also for women who have low risk pregnancies, the outcomes could be different for higher risk pregnancies.

Should all women have access to home birth?
Yes! and no.  I think this data shows that it is safe, under prudent conditions.  All women in the U.S. who are deemed low risk should have high quality home birth care available (ie it shouldn't be illegal).

Do excessive interventions make hospital birth less safe?
Probably.  This particular analysis starts to make a case.  I may analyze this in future posts (I do have a post on epidurals almost completed already), but unfortunately there is not a whole lot of description on why an induction, augmentation or epidural was used so it makes it difficult to definitively say what came first--the intervention or the complication.  The fact that intervention free hospital birth has better outcomes than overall hospital birth alone isn't really indicative, but when combined with the information that a self-chosen group of women, who choose an intervention free birth beforehand (ie a home birth), have similar results provides stronger evidence toward the claim.

What's up with the assisted ventilation immediately after birth?
That was the one adverse event in which happened more often at home (albeit still only 3 percent of the time), than at a hospital.

Information lacking in the data
A neonatal mortality number (baby dies in the first couple months of life) is missing from this data.  This is a number that opponents of home birth commonly use to reflect that home birth is not safe and the fact that it is missing is unfortunate.  The inaccurate Not Alive When Reported number or the too broad infant mortality numbers are the closest we get.  Mother mortality is another number that is missing from the data.

Me/my wife/my baby would have died if I wasn't at a hospital
Yeah, me too.  The distinction that many people do not realize is that having a home birth does not mean the hospital isn't available.  The fact that it is available is what makes home birth safe.   Also, as shown above, the life threatening event is less likely (but not completely unlikely) to occur when you are at home.  Was the emergency caused by bad luck, or due to a bad drug interaction?

For some people the small chance that something really bad will happen, and being in the place it can get treated the quickest, is a more important a factor in deciding where to birth.  For others reducing the more common, though less serious, adverse outcomes is more important.  I believe that the important thing is that every women has the opportunity to receive quality care that aligns with her own risk comfort level.

Freestanding birth centers
I didn't include birth center births because some hospital's attached birth centers got labeled as free standing birth centers.  I didn't feel like picking through them and figure out which were truly free-standing and which were not so I chose to not include them.

What I would like to see
Home birth be legal, regulated, and covered by insurance in all fifty states.  I also think it would be great if CNM's and doctors delivered at home.  There are other things too, but I think they are out of the scope of this post.


Bias
I tried to be unbiased and get a true look at the safety of home birth.  I attempted to address concerns regarding perinatal mortality versus infant mortality.  I tried to include prudent parameters for home birth (ie full-term gestation and with a midwife attending) and only comparing similar demographics in the hospital.  Thus comparing home birth to only very low-risk pregnancies and intervention free births.  I hope that neither side can look at this and say I purposely skewed the data one way or the other.

Soap Box
If a woman decides to have a home birth or a natural birth she is not putting the "experience" ahead of her or her child's safety.  She should not be made fun of (cliche joke on TV), or told that she won't get a medal for doing it natural.  I know birth is tough.  I know home birth and unmedicated birth are not for everyone, nor am I saying that they should be, but women who look at this data and think it is worth it, should not be told they are crazy or that they are putting their child's life in danger, or every other awful  thing people and providers may say.

METHOD

This data comes from the Washington State birth certificate database for the years 2002 - 2007.  Here is a bit more information about me and the data.
  • Confidence Intervals were calculated using this document.  I used Poisson distributions when the number of events was less than 20 (I may have neglected this step, due to laziness, in cases where it was obviously not going to be significant).  It said to use 3 events if 0 events occurred, but this gave me weird results where the CI was statistically significantly higher than the comparative CI when in actuality there were no events recorded.  I switched to using 1 for the high, and zero for the low, and got more meaningful results.  I used the simplistic method in comparing confidence intervals, where statistical significance is only true when the intervals do not overlap.
  • Results were extracted using SQL.  They were copied into Excel where standard errors and confidence intervals were calculated and compared.
  • Each birth was only counted once, if multiple adverse reactions occurred the most severe event was the one recorded (ie if a baby had seizures, NICU stay and then died :(. The seizure and NICU fields would not reflect those events).
  • The adverse reactions recorded for the baby were:
    • adverse - a sum of all the events below
    • death - This does not include still births, but includes any baby that died within the first year of its life.  Whether the death was related to the birth or not is not specified.
    • assist_vent - Assisted Ventilation Required Immediately Following Delivery
    • assist_vent_cont - Assisted Ventilation Required for More Than 6 Hours
    • NICU - NICU Admission
    • surfactant - Newborn Given Surfactant  Replacement Therapy
    • sepsis - Antibiotics received by the Newborn for Suspected Neonatal Sepsis
    • seizure - Seizure or Serious Neurologic Dysfunction
    • birth_injury - Significant Birth Injury
    • intolerance_of_labor - Fetal Intolerance of Labor such that One or More of the Following Actions was Taken:  In-utero Resuscitation Measures, Further Fetal Assessment, or Operative Delivery 
    • meconium - Moderate/Heavy Meconium Staining of the Amniotic Fluid
  • The adverse reactions recorded for the mother were:
    • maternal_adverse - a sum of all the events below
    • transfusion - Maternal Transfusion
    • tear - Third or Fourth Degree Perineal Laceration
    • rupture_uterus - Ruptured Uterus
    • hysterectomy - Unplanned Hysterectomy
    • ICU - Admission to Intensive Care Unit
    • operation - Unplanned Operating Room Procedure Following Delivery
    • initial_cesarean - the birth was via cesarean and the mother had not had a previous cesarean
    • transfer_to_hospital - the mother did not give birth at home, though she intended to.\
  • I could not compare the number of still born babies between home births and intervention free hospital births because the fetal death records do not specify what interventions occurred.
Please let me know if you find any errors, mathematical or otherwise.  I hope this information is helpful and meaningful.  I spent an excessive amount of time producing this so pats on the back are appreciated. :)  Joining Kachingle is a great idea too!

Recommended reading and resources on natural childbirth:

5 comments:

Esther said...

This is a very interesting article and answered some questions I have. Thanks!

Anonymous said...

well done!

thank you. thank you. thank you.

Anjuli said...

Thank you for this amazing analysis- it has helped me tremendously. My daughter will be having a home birth in May- and this has answered many of my thoughts and questions. Thank you for the research (well done).

Becky said...

Is this based on intended place of birth, or actual place of birth? That is, if a transfer from homebirth occurred and baby died, is that death counted in the home or hospital birth numbers?

Laura said...

Becky- The numbers are based on the intended place of birth.