The science of preeclampsia, a serious life threatening medical condition of pregnancy, supports the idea of Biblical marriage.
Preeclampsia is a type of pregnancy induced hypertension (high blood pressure) that can quickly lead to organ damage in the mother, and even death of the baby and/or mother.
A number of studies show that pregnancies in women who have had longer periods of exposure to the baby’s father’s sperm, before getting pregnant, are less likely to develop preeclampsia, compared to women who get pregnant in a short term relationships.
Biblical marriage, with its ideal of a long term relationship between only one man and one woman, increases the likelihood the mother will have multiple exposures to her baby’s father’s sperm before getting pregnant. With each subsequent child they have, there will be an even longer time of pre pregnancy exposure of the mother to the baby’s father’s sperm.
Although the scientific studies do not explicitly look at Biblical marriage they do indicate that longer periods of pre pregnancy exposure by the mother to the father’s sperm decrease the risk.
Now the heavier reading, the evidence. The studies. 
JI Einarsson, et al., Sperm exposure and development of preeclamsia, American Journal of Obstetrics and Gynecology, 2003, 188(5), p 1241. A case-control study comparing 113 cases of women who developed preeclampsia to 226 controls, similar women who did not develop preeclampsia. Women with a short period of cohabitation (<4 months) who used barrier methods for contraception had a substantially elevated risk for development of preeclampsia compared with women with more than 12 months of cohabitation before conception. (39)
PY Robillard, et al., Women with a short period of cohabitation (<4 months) who used barrier methods for contraception had a substantially elevated risk for development of preeclampsia compared with women with more than 12 months of cohabitation before conception, Lancet, 1994, 344(8928), p 973. 1011 consecutive women who delivered in an obstetrics unit were divided into three groups, those with pregnancy induced hypertension, chronic hypertension, and normal blood pressure. The incidence of pregnancy induced hypertension was 11.9% in first pregnancies, 4.7% among second, third, etc. pregnancies from the same father, and 24% among women with second, third, etc. pregnancies from different fathers. Mothers and fathers who stick together are at the lowest risk. The risk for first pregnancies was higher than second pregnancies with the same father, but considering the first pregnancy group was not subdivided into mothers with one faithful man verses those with multiple sexual partners before their first pregnancy. Those with multiple partners are likely to have had shorter times of exposure to the baby’s father’s sperm before pregnancy. (36)
JX Wang, et al., Surgically obtained sperm, and risk of gestational hypertension and pre-eclampsia, Lancet, 2002: 359(9307), p 673. Women who achieved pregnancy by invitro fertilization (IVF) or intracytoplasmic sperm infection (ICSI) (with both of these techniques no sperm enters the women’s body), when compared to those who became pregnant the normal way, were three times more likely to to experience preeclamsia. (38)
GN Smith, et al., Increased incidence of preeclampsia in women conceiving by intrauterine insemination with donor versus partner sperm for treatment of primary infertility, American Journal of Obstetrics and Gynecology, 1997, 177(2), p455. 44 women who achieved their first pregnancy by sperm insemination by their partner were compared with 37 women with their first pregnancy by sperm insemination using donor sperm. Only three cases of mild preeclampsia occurred in the partner sperm group compared with nine (five severe, four mild) in the donor sperm group. (40)
Looking at these studies, a period of sperm exposure within a stable relationship with the baby’s father before pregnancy happens provides some protection against preeclampsia. This is part of what happens in the Biblical ideal of marriage. One of the benefits of Biblical marriage is a decreased risk of getting preeclampsia during pregnancy.
 There are many different factors associated with the development of preeclampsia. Although the science of preeclamsia supports the benefits of Biblical marriage, a Biblical marriage does not guarantee a woman will not get preeclamsia.
 The studies considered in this blog post are those referred to in the UpToDate medical data base under Preeclamsia: Pathogenesis – Immunologic Factors, looked up on Dec 31, 2018. (references can be found in the public page. To read the article a subscription to UpToDate is needed. From what I can tell UpToDate is no biased for or against Biblical marriage. LINK